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Columbia  ^mberStti) 
in  tt)e  Citp  of  ^eto  |?orfe    \<^  \ 


3^cference  l.itirarp 


Principles  and  Practice  of 
Cro^^n  and  J3riage^\^orK 


A  practical,  systematic  and  modern  treatise  upon  the  requirements  and  technique  of  artificial 

crown  and  bridgework. 


WITH  1160  ILLUSTRATIONS 


Fourth   Edition 


BY 

HART  J.  GOSLEE,  B.S.,  D.D.S. 

CHICAGO.  ILL. 


Professor  Prosthetic  Dentistry  and  Crown  and  Bridgework,  Chicago  College  of  Dental  Surgery, 

Formerly  Dental  Surgeon  to  the  Attending  Staff,  Cook  County  Hospital  ;  Foreign  Associate 

Member   Society   of   Dentists   of    Norway ;    Member    International    Dental    Federation ; 

National  Dental  Association  ;   Institute  of  Dental  Pedagogics  ;  Illinois  State  Dental 

Society;   Chicago  Odontographic  Society;    Honorarj'  Member  Ohio  State  Dental 

Society;  South  Dakota  Dental  Society;  New  York  Odontological  Society  and 

Second  District  Dental  Society,  Nev/  York ;  Corresponding  Member  St. 

Louis  Dental  Society,  etc.,  etc. 


NEW  YORK: 
THE  CONSOLIDATED  DENTAL  MFG.  CO. 

LONDON : 

CLAUDIUS  ASH  y  SONS  (LIMITED) . 

1913 


Copyright.  1903. 
Copyrigh-..  1907. 
Copyright,  1910. 
Copyright,  1913. 
By  Hart  J.  Goslee. 
Entered  at  Stationers'  Hall,  London 


\    \\ 


TO    MY   FRIENDS 

TRUMAN   W.  BROPHY,  LL.D.,  M.D.,  D.D.S., 

AND 

RODRIGUES  OTTOLENGUI,  M.D.S.,  LL.D.,  D.D.S., 

In  recognition  of  their  personal  and  professional  attainments,  and  as  a  small 

evidence  of  appreciation  of  their  friendship,  and  of  gratitude 

for  their  counsel  and  assistance 

THIS   BOOK   IS    RESPECTFULLY   INSCRIBED 
BY   THE   AUTHOR. 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 
Columbia  University  Libraries* 


http://www.archive.org/details/principlespractiOOgosl 


Preface. 

The  development  of  the  specialty  of  crown  and  bridgework,  and  par- 
ticularly of  the  methods  of  crowning-  teeth,  has  been  so  rapid  that  it  has 
probably  been  difficult,  if  not  indeed  quite  impossible,  for  the  average  prac- 
titioner to  keep  apace  with  the  numerous  modifications  of,  and  improve- 
ments in,  the  various  methods  of  procedure  which  have  been  constantly 
presented  and  advocated  in  the  evolution  of  this  specialty  from  a  some- 
what chaotic,  and  at  best  unsystematic  beginning,  to  its  present  acknow- 
ledged position  as  a  distmct  and  highly  artistic  and  practical  department 
of  dental  prosthesis. 

It  is  therefore  believed  that  there  is  a  need  at  the  present  time  for 
a  strictly  modern  text  and  reference  book,  embracing  a  tangible,  syste- 
matic and  practical  classification  ot  the  subject,  supplemented  with  ade- 
quate illustrations. 

In  assuming  to  supply  such  a  possible  need  an  efifort  has  been  made 
to  present  the  subject  matter  in  a  practical  and  concise  form,  and  in  a 
more  or  less  systematic  and  sequential  order ;  as  well  as  to  avoid,  in  so 
far  as  possible,  any  consideration  of  methods  which  may  have  proven,  or 
which  are  deemed,  to  be  impracticable ;  or  those  which  m.ay  have  been 
abandoned,  or  have  become  obsolete. 

Special  care  has  been  given  to  the  presentation  of  the  various  methods 
which  are  practiced,  and  which  are  recognized  as  possessing  merit  and 
practicability.  This  is  deemed  warrantable,  and  indeed  essential,  for  the 
reason  that  in  the  successful  practice  of  a  specialty  in  which  a  very  high 
order  of  art  and  mechanics  is  demanded,  and  which  involves  more  or  less 
permanent  application  as  a  part  of  the  human  economy,  where  the  con- 
ditions presenting  are  so  greatly  diversified,  there  is  no  one  best  method. 
Some  procedures  will  be  found  more  applicable  to  one  case  than  to 
another,  and  to  be  more  practical  and  successful  in  some  hands  than  in 
others. 

Personal  equation  and  good  judgment  will  dictate  and  enter  largely 
into,  the  application  of  the  most  practical  method  to  be  pursued  in  each 
case,  and  this  will  usually  have  as  much  bearing  upon  the  success  and 
serviceability  of  the  operation  contemplated,  as  will  the  degree  of  skill 
which  may  be  exhibited  in  the  execution  of  the  details  of  construction. 


The  various  methods  and  technique  of  modern  procedures  are  pre- 
sented and  commented  upon  from  an  original  and  unbiased  viewpoint. 
This  is  done  with  the  behef  that  their  respective  apphcation  and  practic- 
ability will  thus  probably  be  more  logically  elucidated ;  and  that  their 
merits  will  be  less  likely  to  be  overestimated,  than  if  they  were  presented 
in  the  language  of  the  original  advocate,  because  of  the  enthusiasm  which 
would  thus  naturally  tincture  the  claims  made  for  them. 

In  so  far  as  possible  every  effort  has  also  been  made  to  acknowledge 
and  give  due  credit  as  to  the  origin  of  the  many  valuable  and  ingenious 
ideas  and  suggestions  which  have  aided  so  much  in  the  development  of 
this  class  of  work,  and  in  placing  this  specialty  upon  a  somewhat  sound, 
systematic  and  practical  basis ;  as  well  as  to  those  which  have  served  to 
facilitate  and  expedite  the  procedure  and  to  relieve  the  patient  of  any 
unwarranted  or  unnecessary  discomfiture  incident  to  the  operation. 

Where  several  similar  methods  of  detail  are  mentioned  in  connection 
with  a  single  mode  of  procedure,  they  are  invariably  placed  in  the  order 
of  their  preference,  unless  otherwise  emphasized  in  the  text. 

All  reference  to  the  therapeutic,  or  surgical  technique  possibly  indi- 
cated in  the  treatment  of  pathological  conditions  involving  the  roots  of 
teeth,  or  surrounding  tissues,  has  been  purposely  avoided,  in  the  belief 
that  such  matter  more  properly  belongs  to  works  on  therapeutics  per  se, 
rather  than  to  a  book  which  is  designed  only  as  a  practical,  and  compre- 
hensive elucidation  of  the  principles,  practice  and  technique  of  modern 
methods  of  crowning  teeth. 

Hart  J.  Goslee. 

Chicago,  111.,  April  30th,  1903. 

PREFACE  TO  SECOND  EDITION. 


In  revising  the  first  edition  the  changes  and  additions  demanded  by 
the  advance  of  time,  and  the  progress  made,  were  surprisingly  few.  This 
is  particularly  gratifying  to  the  author,  and  he  is  deeply  grateful  to  the 
profession  for  its  approval  and  support  of  his  efforts. 

The  addition  of  the  Chapters  on  Bridgework,  and  the  change  of  title 
made  necessary  thereby,  are  but  a  part  of  the  original  plan  which  was  un- 
avoidably delayed  because  of  the  amount  of  work  involved  in  an  effort  to 
present  with  some  definite  and  practical  classification  and  system,  a  subject 
which  has  heretofore  been  little  less  than  a  "bewildering  and  chaotic  mass 
o^  details,"  and  consequently  j)rimitive  and  empirical. 

As  applied  to  l>ridgework  this  is  particularly  true,  and  while  the 
growth    and   development   of   this   specialty   has   been   nothing   short   of 


phenomenal,  and  while  many  of  the  bright  minds  of  the  profession  have 
contributed  toward  its  progress,  yet,  there  has  always  been  a  lack  of  co- 
ordination of  thought,  and  co-operation  of  effort  such  as  would  result  in 
a  practical  classification  of  requirements,  methods  and  results,  and  with- 
out which  the  whole  application  must  otherwise  remain  tinctured,  as  it 
were,  with  empiricism. 

In  view  of  the  possibilities  of  this  specialty  as  an  art,  and  of  its 
importance  as  a  means  of  reuniting  and  inseparably  binding  together 
all  of  the  various  departments  of  practical  dentistry,  and  thus  aiding  in 
the  further  development  of  the  profession  as  a  whole,  and  for  the  reason 
that  in  previous  attempts  no  general  system  has  obtained  and  no  unifica- 
tion of  principles  has  prevailed,  such  an  effort  was  thought  to  be  needed, 
and  has  been  the  object  and  the  inspiration  of  this  work  from  the  very 
beginning.  If,  therefore,  it  should  but  aid  in  placing  artificial  crown  and 
bridgework  on  a  broader  scientific  and  practical  basis,  where  so  high  and 
useful  an  art  properly  belongs,  and  must  ultimately  be  placed,  the  result 
will  more  than  repay  the  eft'ort.  Hart   T.  Goslee. 

Chicago,  111.,  February  lo,  1907. 

PREFACE  TO  THE  THIRD  EDITION. 


Aside  from  the  fundamental  principles  and  particularly  in  so  far 
as  the  technique  of  construction  is  concerned,  the  practice  of  crown  and 
bridgework  has  been  so  completely  revolutionized  by  the  application 
of  the  casting  process  as  to  render  many  of  the  former  modes  of  pro- 
cedure almost,  if  not  entirely,  obsolete,  and  to  demand,  therefore,  a 
careful  and  comprehensive  consideration  of  the  improved  and  more 
modern  methods. 

Although  it  be  true  that  in  almost  every  application  to  the  technique 
of  construction,  much  better  results  have  been  made  possible,  and  are 
now  to  be  obtained  by,  or  in  combination  with,  the  casting  process,  in 
some  form  or  other,  nevertheless,  our  former  methods  of  procedure 
will  always  be  of  practical  value  as  a  means  of  aft'ording  a  broad 
knowledge  of  the  subject,  and  be  more  or  less  useful  as  a  matter  of 
record  and  reference. 

Indeed,  all  methods,  even  including  those  which  may  now  perhaps 
be  obsolete,  have  served  as  stepping-stones  to  the  present  statu?  of  the 
art,  and  whilst  the  experts  in  crown  and  bridgework  to-day  might 
seriously  look  upon  some  of  them  as  quite  useless,  still  it  must  be 
remembered  that  their  own  knowledge  of  the  subject  in  general,  and  tlie 
degree  of  skill  which  they  have  acquired,  has  come  to  them  through 
working  with  these  other  methods. 


Hence  the  efforts  of  the  teacher  will  be  enhanced  by  duly  explaining 
all  the  older  methods,  together  with  the  newer  ones,  thus  leading  the 
mind  of  the  student  to  a  better  comprehension  of  the  evolution  which 
has  taken  place.  And,  moreover,  if  these  older  methods  should  be 
entirely  cast  out  of  the  literature,  it  is  possible  that  in  the  not  distant 
future  they  might  be  brought  forward  again  as  new. 

It  is,  therefore,  gratifying  to  the  author  that  the  second  edition 
should  have  been  exhausted  at  a  time  when  the  possibilities  for  improve- 
ment are  so  conspicuously  apparent,  and  becoming  so  generally  recognized ; 
and  when  the  addition  of  a  chapter  embracing  the  application  of  the 
casting  process  is  so  essential  to  a  modern  consideration  of  the  subject. 

In  presenting  the  third  edition  the  author  has  made  every  effort 
to  emphasize  the  splendid  achievements  and  far-reaching  possibilities  of 
this  process  as  applied  to  crown  and  bridgework ;  to  encourage  and 
stimulate  an  appreciation  of  them,  and  by  such  addition,  together  with 
a  careful  revision  of  the  former  editions,  to  keep  the  work  up  to  the 
systematic  standard  and  high  ideals  which  have  heretofore  directed  his 
eft'orts  and  been  his  chief  ambition. 

Hart  J.  Goslee. 

Chicago,  111.,  August  22,  1910. 


PREFACE  TO  THE  FOURTH  EDITION. 


The  appearance  of  the  fourth  edition  at  this  time  becomes  necessary 
because  former  editions  have  been  exhausted.  This  is  gratifying  to  the 
author  for  the  reason  that  it  enables  him  to  keep  the  book  up  to  the 
very  latest  moment,  which  has  always  been  one  of  his  ambitions,  and 
which  is  necessary  in  these  days  of  rapid  progress  and  advancement.  It 
is  also  gratifying  because  it  bespeaks  an  appreciation  on  the  part  of  prac- 
titioners, teachers  and  students  which  is  encouraging. 

The  addition  of  the  more  modern  methods  of  removable  bridge- 
work,  and  of  the  author's  own  methods  and  technic  of  crown  construc- 
tion, indicate  the  extent  to  which  the  casting  process,  together  with  other 
contriljutory  improvements,  has  revolutionized  our  methods  of  practice, 
all  of  which  was  prophesied  from  the  very  advent  of  this  process. 

With  these  improvements  former  empirical  methods  have  been  sup- 
planted to  such  an  extent  as  to  make  it  possible  to  practice  artificial  crown 
and  bridgework  along  more  or  less  definite  and  systematic  lines,  and  it 
is  hoped  that  the  full  possibilities  of  the  present  day  will  be  grasped  and 
applied,  and  that  more  system  and  method  in  this  line  of  work  will  be 
cultivated  and  developed.  Hart  J.  Goslee. 

Chicago,  March  4,  1913. 


Principles  and  Practice  of  €rown 
and  Bridgework. 


l)i$tory  ana  Development  of  grown  UlorK. 


CHAPTER  I. 

Primitive  Application  of   Crowns.     First  Application  of   Porcelain   Crowns.     The 

Use  of  English  Tube-Teeth   for  Crowns.     The  Foster  Crown.     The  Mack 

Crown.    The  Shell  or  Telescope  Crown.    The  Gates-Bonwill  Crown.     The 

Howland-Perry  Crown.    The  'Richmond  Crown.    The  Bhttner  Crown. 

The  How  Crown.    The  Weston  Crown.    The  Logan  Crown.    The 

Brown  Crown.   The  Webb  Crown.  Application  of  Porcelain  to 

Crown  Work.    Various  Modifications  of  These  Principles. 


While  dental  literature  as  early  as  the  beginning  of  the  eighteenth 
century  records  instances  of  the  application  of  piz'ot  teeth  to  roots,  the 
practical  introduction  of  artificial  substitutes  for  the  natural  crowns  of 
teeth  lost  through  accident,  or  by  the  process  of  caries,  and  the  ultimate 
development  of  crown  and  bridgework  is  purely  the  product  of  the  last 
half  of  the  nineteenth  century,  and  must  be  placed  to  the  credit  of  Ameri- 
can dentistry. 

As  the  profession  itself  has  from  humble  environments  grown  and 
broadened  into  a  scientific  calling  with  marvelous  rapidity,  so  also  has 
the  specialty  of  crown  and  "bridgework,  the  evolution  of  the  application 
and  construction  of  which  forms  an  interesting  chapter  in  anv  history  of 
the  conception,  progress  and  advancement  of  all  that  pertains  to  dental 
art  and  prosthesis. 

Besides  opening  new  fields  for  higher  artistic  conceptions,  it  has 
also  materially  affected  the  general  advancement  of  the  profession,  for 
at  one  time  it  seemed  propitious  and  apparently  inevitable  that  the  latter 
should  become  divided  into  the  separate  branches  of  operative  and  me- 
chanical dentistry,  and  that  it  would  be  the  exception  rather  than  the  rule 


b 


for  the  average  person  to  attain  a  degree  of  proficiency  in  both  branches  so 
dissimilar  to  one  another. 

This  speciahy,  however,  then  just  budding  into  general  favor  by  the 
recognition  of  its  possibilities,  and  so  equally  dividing  the  labor  involved 
between  the  mind  and  the  hand,  the  chair  and  the  laboratory,  soon 
proved  the  fallacy  of  such  thoughts,  and  resulted  in  reuniting  these 
branches,  thus  greatly  encouraging  the  unprecedented  advance  which 
the  profession  has  since  made. 

To  crown  and  bridgework  also  can  be  attributed  much  of  this 
progress,  for  no  field  in  art  or  mechanics  ofl^ers  greater  opportunity  for  the 
display  of  individual  skill  and  artistic  attainments. 

The  employment  of  these  talents  in  any  line  cultivates  the  finer  in- 
stincts, promotes  a  higher  sense  of  appreciation  of  nature,  and  draws  a 


Fiq  .  I.  ' 

fine  line  of  distinction  between  the  tradesman  or  artisan  and  the  true 
artist ;  and,  in  the  province  of  dentistry,  enables  one  to  more  nearly  imi- 
tate, and  often  improve  upon,  the  normal  or  abnormal  conditions  which 
lend  so  much  to  the  appearance  and  comfort  of  those  who  might  other- 
wise be  prematurely  disfigured  or  permanently  subjected  to  discomfiture. 

From  available  records  the  first  application  of 
Primitive  Jlpplication    "pivot  teeth"  is  described  in  Fauchard's  work,  pub- 
Ot  C"Owns.  lished  in  172S,  in  which  mention  is  made    of  a  crown 

fastened  to  the  root  with  a  pivot,  and  which  con- 
sisted of  a  crown  carved  out  of  bone  or  ivory,  or  one  of  a  natural  tooth, 
mounted  ujjon  the  root  with  a  roughened  pivot  of  silver  or  gold.  The 
interior  of  the  root  was  first  filled  with  lead,  into  the  center  of  which  a 
hole  was  afterward  drilled  for  the  reception  of  the  pivot,  the  other  end  of 
which  had  been  previously  cemented  in  a  hole  in  the  crown.     I'ig.  i. 

In  the  work  of  de  Chemant,  published  in  1816, 
Tirst  J!;7piication       nearly  one  hundred  years  later,  much   reference   is 
of  made  to  the  use  of  "mineral  paste,"  and  a  brief  de- 

Porcelain  Crowns.      scri])lion  is  gi\cn  of  "a  single  tooth  with  pivot,"  ac- 
companied with  a  crude  illustration,  which  indicates 
that  it  was  intended  as  a  crown  to  be  attached  to  a  root.     iMg.  2. 


While  other  designs  of  "mineral"  teeth  were  subsequently  recorded 
in  French  literature,  in  which  country  porcelain  was  first  applied,  it  was 
not  until  about  1840  that  much  effort  was  made  toward  the  preservation 
of  broken-down  roots,  or  much  thought  given  to  the  problem  of  restor- 
ing lost  crowns  of  teeth,  the  prevailing  and  common  practice  having 
been  to  extract  them  and  insert  plates ;  or,  in  some  instances,  to  grind 
them  down  even  with  the  tissues  and  retain  them  for  the  purpose  of 
preventing  alveolar  absorption. 

About  this  time  more  progressive  and  esthetic 
6n9li$b  ideas   were   conceived   which   resulted   in   the   intro- 

tUbC  Ccetb.  duction  and  first  practical  application  in  this  country 

of  artificial  crowns,  in  the  form  of  the  English  tube- 
teeth,  designed  and  previously  used  for  plate  work.  These  were  ground  to 
fit  the  root  and  mounted  with  pivots  of  hickory  wood.  This  was  con- 
ceded to  be  a  marked  step  in  advance — a  revelation  indeed — and  proved 


Fiq.3. 


ricf.4. 


the  formative  period  of  that  class  of  work  which  was  destined  to  develop 
into  such  an  important  specialty.  But  the  theory  of  the  wooden  pivot 
serving  as  a  means  of  anchorage  by  virtue  of  the  expansion  incident  to 
the  absorption  of  moisture  soon  proved  impracticable,  because  of  the  in- 
adequate stability,  and  not  infrequent  occurrence  of  fractured  roots  as  a 
result  of  the  swelling  of  the  wood,  as  well  as  the  necessary  presence  of 
moisture  which  induced  decay.    Fig.  3. 

Some  modifications  of  this  method  are  recorded  whereby  eiTort  was 
jnade  to  overcome  the  objectionable  features  and  permit  of  the  removal 
of  the  crown  in  order  to  facilitate  the  treatment  of  the  roots,  which  devel- 
oped into  a  necessity  as  the  result  of  sealing  them  up  without  proper 
aseptic  considerations. 

The  most  prominent  of  these  were  the  crown  attachment  patented  in 
1844  by  Dr.  J.  S.  Dodge,  which  consisted  of  mounting  a  wooden  tube 
mto  the  root  and  attaching  a  metal  dowel  to  the  crown  with  plastics,  which 
fitted  closely  into  the  cylinder  of  wood,  yet  rendered  its  removal  easy; 
and  the  design  of  Dr.  F.  H.  Clark,  patented  in  1849  and  comprising  the 
insertion  of  a  metal  tube  in  the  root  which  was  anchored  securely  with  a 


large-h^ded  screw-pivot,  perforated  through  the  center  to  allow  accu- 
mulated gases  to  escape.  To  the  projecting  or  free  end  the  crown  was 
attached. 

Because   of    the    tendency    of    these    crowns    to 
the  loosen  in  their  attachment  to  the  pivot,  and  the  ob- 

Tostcr  0rowtt.  jections  to  wooden  pivots,  the  Foster  crown  was  pat- 
ented in  1855,  and  Avhile  constructed  upon  almost 
the  same  lines  as  one  designed  some  five  years  preceding  it,  by  Dr. 
Henry  Lawrence,  it  enjoyed  quite  an  extensive  use  for  a  number  of  years 
under  the  former  name.  It  possessed  almost  a  flat  base,  with  a  perfora- 
tion in  the  body  of  the  porcelain  so  shaped  as  to  form  a  seat  for  the  ac- 
commodation of  the  enlarged  head  of  a  screw-pivot,  by  which  means  it 
was  anchored  securely  to  the  root.     Fig.  4. 


Ficj 


.5. 


Fi 


7- 


While  in  the  former  styles  the  dowel  was  first 
C1)C  ntack  €rown.  attached  to  the  crown  and  then  subsequently  to  the 
root,  the  design  of  Dr.  C.  H.  Mack,  patented  in 
1872,  is  recorded  as  the  first  instance  where  the  dowel  was  attached  firmly 
in  the  root  before  the  crown  was  fixed  in  place  upon  it.  The  crown  was 
constructed  with  a  countersunk  cavity  in  the  body  of  the  porcelain  which, 
being  filled  witli  plastics,  anchored  it  securely  when  mounted.     Fig.  5. 

The  difficulty  experienced  in   adapting  any  of 
CbC  Shell  the  former  styles  to  the  ])osterior  teeth  in  a  practical 

or  or  permanent  manner,  and  the  desirability  of  restor- 

tclcscope  Crown.       ing    and    preserving    their    normal    functions,    ulti- 
mately led  to  the  invention  of  the  gold  shell  or  tele- 
scope crown,  patented  by  Dr.  J.  B.  Beers  in  1873,  though  probably  first 
suggested  by  Dr.  W.  N.  Morrison  some  few  years  previously. 

This  crown  proved  a  great  step  in  the  line  of  progress  and  develop- 
ment, because  the  construction  did  not  require  the  sacrificing  of   tooth 


structure  to  the  extent  necessary  for  porcelain  crowns,  and  made  pos- 
sible the  better  and  more  serviceable  reproduction  of  natural  tooth  forms. 
The  seam  of  union  between  crown  and  root  was  for  the  first  time  carried 
under  or  within  the  free  margin  of  the  gum  and  apparently  made  the 
operation  a  more  permanent  success  than  had  theretofore  seemed  pos- 
sible.    Fig.  6. 

The  success  and  practicability  of  this  style  of  crown  has  resulted  in 
the  subsequent  invention  from  time  to  time  of  innumerable  systems  and 
methods  of  construction,  all  of  which  while  varying  in  detail  accomplish 
practically  the  same  end ;  and,  while  it  has  done  much  to  prove  the  ad- 
visability of  encompassing  the  end  of  the  root  with  a  band,  and  to  a  great 
extent  made  possible  the  ultimate  success  of  permanent  stationary  bridge- 
work,  its  virtues  have  been  most  grossly  abused  in  their  application  to 
anterior  teeth,  and  through  their  production  in  ready-made  form,  the  use 
of  which,  in  justice  to  the  artistic  possibilities  within  the  reach  of  the 
modern  dentist,  cannot  be  too  vigorously  condemned. 


Ficj  ■  7.  Ficj.  8. 

As  the  result  of  the  more  or  less  successful  ex- 

tbc  periment  with  the  Foster  and  Mack  crowns,  an  im- 

Gates-Bonwill  Crown,      provement   subsequently   appeared   in   a  tooth   that 

became  known  as  the  Gates-Bonwill  crown,  a  patent 

having  been  issued  to  Dr.  W.  H.  Gates  in  1875,  and  to  Dr.  W.  G.  A. 

Bonwill  in  i8(Si,  covering  practically  the  same  ideas. 

This  crown  was  of  porcelain,  constructed  with  a  concave  instead  of 
a  flat  base,  and  having  a  triangular  perforation  through  the  body  of  the 
porcelain,  afforded  a  better  and  more  secure  means  of  attachment  to  the 
root,  to  which  it  was  secured  by  means  of  a  metal  dowel  which  was 
threaded  and  screwed  into  the  canal,  after  which  the  crown  was  anchored 
with  amalgam.     Fig.  7. 

Shortly  after  this  the  Rowland  crown,  subse- 

tftC  l)OWlancl-         quently  modified  by  Dr.  S.  G.  Perry,  and  styled  the 

Perry  Crown.         I  lowland-Perry  crown,   was  suggested.     This  was 

very  similar  to  the  preceding  ones,  but  differed,  like 

the  Mack  crown,  in  that  the  accommodation  for  the  dowel  was  confined 

to   a   cavity   in    the  body   of   the   porcelain,   instead   of   passing  entirelv 

through   it.      This    followed    the   then   developing   tendency   toward    the 


esthetic,  by  the  preservation  of  the  continviity  of  the  exposed  surfaces  of 
porcelain,  not  disclosing  the  end  of  the  metal  dowel  or  the  mounting 
material.    Fig.  8. 

This  design  was  patented  by  Dr.  C.  M.  Rich- 

tbe  mond  in  1880,  and  consisted  of  a  cap  encompassing 

Richmond  Crown.       the  end  of  the  root,  to  which  a  facing  similar  to  the 

ordinary  plate  tooth  was  attached  by  soldering.    This 

was  the  first  practical  application  of  a  band  to  a  root  for  anterior  crowns 

with  porcelain  facings. 

As  originally  designed,  it  consisted  of  a  band,  to  which  was  soldered 
a  floor,  forming  a  cap.  To  this  was  then  attached  a  facing  hollowed  out 
between  the  pins  so  as  to  accommodate  a  threaded  dowel  which,  passing 


Fij/.Q 


P  1^.10. 


through  the  cap,  was  then  screwed  into  a  tube  previously  mounted  in  the 
canal,  thus  attaching  the  crown  to  the  root.     Fig.  9. 

While  it  was  then  for  some  time  a  matter  of  doubt  and  conjecture 
as  to  the  advisability  of  banding  the  anterior  teeth,  and  as  to  whether  it 
was  an  objectionable  or  an  advantageous  procedure,  the  original  principle 
was  soon  abandoned  because  of  the  intricate  and  unstable  manner  of 
attachment,  and  the  apparent  uselessness  of  a  separate  dowel,  but  the 
modifications  and  improvements  resulting  from  this  suggestion  are  now 
conceded  to  be  the  best  means  of  securing  permanence  in  the  operation, 
and  are  the  accepted  practice  of  today. 

During  the  early  agitation  of  the  feasibility  of 
Z\)t  banding.  Dr.  IT.  W.  Riittner  invented  a  metal  and 

Blittner  Crown,        i)orcelain   crown  with  a  band  wherein  the  method 
employed  in  attaching  it  to  the  root  would  possess 
the  advantages  of  a  band,  and  at  the  same  time  preclude  its  possible  irri- 
tating influences. 


This  was  accomplished  by  trephining  the  periphery  of  the  end  of 
the  root  to  form  suitable  accommodation  for  the  band,  with  instruments 
specially  devised  for  the  purpose,  but  the  idea  never  met  with  universal 
favor,  and  it  was  soon  abandoned.     Fig.  lo. 

A  crown  devised  by  Dr.  W.  S.  How  in  1883 
the  Bow  Crown.  consisted  of  a  thin  facing  with  four  pins  and  a  slotted 
back  for  the  reception  of  the  "screw-post,"  which 
was  anchored  to  the  facing  by  bending  the  pins  over  it  after  it  was  backed 
up,  and  the  desired  contour  was  then  built  up  with  solder.  The  extreme 
thinness  and  consequent  weakness  of  the  porcelain  rendered  its  usefulness 
limited.    Fig.  11. 


f'q  .11. 


Fiq.12. 


Fiq.13. 


Another    similar    form    was    invented   by    Dr. 

tbC  Henry  Weston  in  1883  and  subsequently  modified. 

(Ueston  Crown.         The  first  design  comprised  a  means  of  attaching  the 

dowel  to  the  facing,  which  is  best  described  by  the 

illustration,  after  which  it  was  attached  to  the  root.    Fig.  12. 

In  the  modification  the  dowel  was  first  securely  fixed  in  the  root  and 
then  the  crown  which  was  constructed  with  a  view  of  being  much 
stronger,  was  held  in  contact  with  the  root,  and  anchored  by  packing 
through  an  opening  for  the  purpose,  on  the  lingual  surface.     Fig.   13. 

It  will  be  observed  that  up  to  this  time  the  various  steps  in  the  de- 
velopment of  the  work  consisted  of  a  crown  and  dowel  as  two  separate 
parts,  but  here  a  deviation  in  the  principle  was  made  for  the  purpose  of 
securing  additional  strength,  in  which  the  dowel  became  an  integral  part 
of  the  crown  by  being  baked  in  the  body  of  the  porcelain. 

This  crown  the  first  to  be  so  constructed,  was 

CbC  Cogan  Crown,      tlie  invention  of  Dr.  M.  L.  Logan,  patented  in  1885. 

and  made  with  a  large  body  of  porcelain  having  a 

concave  countersunk  base  to  facilitate  adaptation  to  root,  and  a  dowel 

shaped  more  in  line  with  scientific  principles.     ]\Iore  nearly  approaching 


8 


the  requirements  in  conformation  than  any  of  its  predecessors,  it  soon 
became  very  popular,  eventually  supplanting  all  other  designs  of  similar 
nature,  and  for  years  has  had  an  extensive  use  and  application.     Fig.  14. 

Another  design  was  shortly  afterward  evolved 

CbC  Brown  Crown,     and  introduced  by  Dr.  E.  Parmley  Brown,  and  while 

of  the  same  type,  it  possessed  a  base  convex,  instead 

of  concave,  with  a  view  of  affording  by  means  of  its  construction,  the 

greatest   possible    strength   at    the    seam   of   union    between   crown    and 

dowel,  and  crown  and  root. 

Its  adaptation  to  the  root  after  cutting  it  down  properly  was  made 
by  using  a  bur  which  produced  a  concavity,  to  accommodate  the  con- 
vexity of  the  base  of  the  crown ;  but  the  increased  strength  of  the  crown 
being  secured  at  the  expense  of  the  root,  soon  resulted  in  its  abandon- 
ment.    Fig.     15. 


Fiq.l4. 


Fi 


cf.l5. 


Fiq .  16 


The  difficulty  of  grinding  one  surface  to  closely 
CbC  UlCbb  Crown.  approximate  another,  and  the  conceded  advantages 
of  a  close  union  between  crown  and  root,  soon  stim- 
ulated a  desire  to  secure  better  adaptation,  and  resulted  in  the  sugges- 
tion of  a  plate  and  dowel  crown  probably  first  used  by  Dr.  M.  H.  Webb. 

This  was  constructed  by  swaging  or  burnishing  a  metal  plate  to 
the  end  of  the  root,  then  perforating  it  to  admit  of  inserting  into  the 
canal  a  dowel,  which  was  soldered  to  the  plate,  to  ">,vhich  the  facing  was 
then  attached.  The  possibilities  of  adaptation  and  its  advantages  have 
become  so  recognized  that  many  still  so  construct  their  crowns,  and 
they  are  frequently  indicated.    Fig.  16. 

Soon,  however,  the  advancement  of  the  profession  along  those  linesr 
leading  to  the  achievement  of  the  very  highest  conceptions  of  art,  indi- 
cated a  tendency  to  observe  the  maxim  "true  art  is  to  conceal  art,"  and 
created  a  desire  for  something  that  might  supersede  the  use  and  display 
of  gold,  something  more  nearly  resembling  and  harmonizing  with  nature, 
yet,  still  serving  the  same  purposes.  Even  in  this  the  inventive  genius 
of  the  profession  was  not  long  in  again  asserting  itself,  and  soon  after- 
ward came  the  application  of  vitrified  porcelain. 


The  first  suggestions  were  perhaps  made  by  Dr.  C.  H.  Land,  and  were 
eagerly  studied  and  enthusiastically  applied  with  varying  degrees  of  success 
and  failure.  Dentures  of  platinum  and  porcelain  had  been  constructed  and 
worn  successfully  for  years,  hence  it  was  readily  believed  that  crowns 
and  bridges  of  the  same  must  also  of  necessity  be  equally  successful.  In 
this,  however,  many  were  doomed  to  disappointment,  and  because  of 
inadequate  knowledge  of  the  requirements,  too  much  confidence,  and 
the  over-zealous  enthusiasm  of  early  advocates,  its  use  and  practicability 
soon  became  questionable,  and  was  eventually  discontinued  by  the  great 
majority. 

There  were  those,  however,  who,  still  admiring  its  esthetic-beauties, 
and  having  faith  in  its  possibilities,  sought  to  ascertain  the  causes  of 
failures,  and  the  reasons  for  success,  with  the  result  that  its  more  recent 
and  modern  application  has  approached  and  made  possible  the  very 
highest  degree  of  perfection  in  dental  art  and  prosthesis.  Yet  it  is 
not  universally  applicable,  and  will  never  supersede  the  use  of  gold.  The 
success  of  each  must  always  depend  in  a  great  measure  upon  the  sound 
reasoning,  good  judgment  and  skilful  execution  and  discrimination  with 
which  they  are  respectively  applied. 

It  will  be  observed  that,  from  the  very  beginning,  the  innate  and 
intuitive  desire  for  the  practical  and  esthetic  development  of  this  work 
to  more  perfectly  meet  the  demands  and  requirements  of  the  times,  has 
resulted  in  the  presentation  of  many  varied  principles  and  methods,  among 
which  may  be  also  included  the  jacket  crowns;  the  application  of  por- 
celain facings  to  shell  or  telescope  crowns ;  the  Logan  crown  with  the 
addition  of  a  band ;  the  various  modifications  of  the  porcelain  crown 
with  separate  dowel,  such  as  the  Davis  crown,  the  intradental  band 
and  similar  designs,  and  a  galaxy  of  other  varying  and  ingenious  ideas. 
Yet  they  are  in  the  main  but  modifications  of  the  original  principles 
enumerated,  and,  while  aiding  materially  in  the  evolution,  and  showing 
the  trend  of  the  development  and  progress  of  crown  w'ork  from  its 
inception,  their  individual  description  would  be  redundant  and  unneces- 
sary. 

Those  of  practical  value,  use  and  application  at  the  present  time  can 
be  treated  to  better  advantage  elsewhere  than  in  a  brief  resume  of  the 
development  and  history  of  this  work,  which  is  intended  only  to  show 
the  perseverance  and  ingenuity  of  our  predecessors,  and  the  various 
steps  in  making  possible  the  success  of  modern  crown  work,  for  which 
their  eftorts  were  primarily  responsible. 


IDetdls,  Jllloys  and  Solders. 


CHAPTER  II. 

Symbol  and  Fusing  Point  of  Metals  Used.     Noble  and  Base  Metals.    Chemical  and 

Physical  Properties :   Chemical  Action,  Color,  Odor  and  Taste,  Fusibility, 

Malleability,    Ductility,   Tenacity.     Physical    Processes :    Soldering, 

Welding,   Annealing,   Tempering,  Alloying,   Troy  Weight. 

Consideration  of   the  Metals :  Gold,  Karat,  Platinum,  Iridium.     Alloys :  Alloys  of 

Gold,  Coin  Gold,  Gold  and  Platinum,  Platinized  Gold.     Solders :  Platinum 

Solder,      Gold      Solders,      Compounding      Solders,      Brass,      Dor- 

rance's  Alloy,  Silver  Solder,  German  Silver,  Fusible  Alloys, 

Soft   Solder,   Refining   Gold,   Etc. 


One  of  the  first  essential  duties  incident  to  the  successful  execu- 
tion of  any  line  of  work  in  art  or  mechanics  is  a  thorough  practical 
knowledge  of  the  materials  used ;  hence,  in  the  construction  and  appli- 
cation of  crown  and  bridge  work,  wherein  the  use  and  manipulation 
of  the  metals  and  their  combinations  forms  such  an  important  feature, 
it  is  materially  necessary  that  the  dentist  should  be  acquainted  with 
their  characteristics,  physical  properties  and  methods  of  manipulation. 

This  is  imperative  only  that  he  may  the  better  understand  their 
application,  for  it  no  longer  becomes  necessary  for  him  to  be  an  expert 
metallurgist,  to  refine  or  alloy,  prepare  or  roll  his  plate  material,  or  to 
combine  and  make  his  solders,  alloys,  etc.,  since  the  manufacturers  and 
supply  houses  now  furnish  them  in  all  grades  desired ;  yet  a  practical 
knowledge  of  the  methods  and  detail  of  manipulating  them  serves  to 
cultivate  and  make  possible  their  more  skilful  application. 

Of  the  fifty-two  metallic  elements  known  to,  and  so  classified  in 
chemistry,  but  a  few  of  them  in  their  melallic  form  are  used  in  the  me- 
chanics and  arts  pertaining  to  dentistry;  hence,   in  this  connection  it  is 


II 


only  necessary  to  refer  to  or  consider  those  the  physical  properties 
and  characteristics  of  which  are  of  common  use  and  application  for 
practical  purposes,  and  which  are  contained  in  the  following  table : 


Name. 

Symbol. 

Fusing 

Point. 

Fah. 

Cent. 

I.  Gold. 

Au. 

2016 

1 102 

2.  Platinum. 

Pt. 

3632 

2000 

3.  Iridium. 

Ir. 

More  refractory 

than  Pt. 

4.  Copper. 

Cu. 

1996 

1091 

5.  Silver. 

Ag. 

1873 

1023 

6.  Zinc. 

Zn. 

773 

412 

7.  Lead. 

Pb. 

617 

326 

8.  Tin. 

Sn. 

442 

228 

9.  Bismuth. 

Bi. 

507 

264 

10.  Cadmium. 

Cd. 

442 

228 

II.  Antimony. 

Sb. 

842 

450 

12.  Aluminum. 

Al. 

1292 

700 

13.  Iron. 

Fe. 

3000 

1600 

14.  Nickel. 

Ni. 

3000 

1600 

noble  and  Base 
metals. 


Classification. 

Metallurgy  divides  the  metals  into  two  groups 
known  as  the  noble  and  the  base,  so  classified 
because  of  their  affinity  for  and  property  of  com- 
bining with  oxygen. 
The  former,  having  less  affinity,  do  not  so  readily  combine  with  it 
by  absorption  from  the  atmosphere,  and  are  more  easily  separated  from 
its  combination  when  subjected  to  heat;  while  the  latter,  having  a  greater 
affinity,  and  absorbing  it  more  readily,  are  separated  with  much  more 
difficulty  because  their  compounds  are  not  decomposed  by  heat  alone. 

Noble  Aletals.  Base  Metals. 

Gold.  Copper.  Cadmium. 

Silver.  Tin.  Antimony. 

Platinum.  Zinc.  Aluminum. 

Iridium.  Lead.  Iron. 

Bismuth.  Nickel. 


12 

CDcmicaJ  and  Pbysical  Properties. 

While  all  metals  possess  distinct  individual  properties  characteristic 
of  themselves,  it  becomes  necessary  for  us  to  consider  only  those  of  such 
practical  importance  as  render  them  useful  and  applicable  to  our  pur- 
While  all  metals  are  more  or  less  susceptible 
Cbcmical  Hction.       to  the  action  of  the  secretions  of  the  mouth,  gold 
and   platinum   are  the  least   so,   and   of  these  two 
platinum   always   withstands   this   influence   and    retains   its   color   much 
better  than  gold,  which  is  due  mainly  to  the  fact  that  platinum  is  com- 
monly used  in  the  pure  state,  and  gold  in  the  alloyed  state. 

Each  metal  possesses  a  characteristic  color,  va- 

gOlor,  rying  from  the  grayish-white  of  silver  and  platinum 

to    the   muddy   blue   of    lead ;    and    from    the    rich 

bright  yellow  gold  to  the  dark  red  of  copper;  each  of  which  is  always 

modified  more  or  less  by  alloying. 

Gold  and  platinum,  however,  possess  a  metallic  lustre  and  colors 
which  are  in  contrast  more  pleasing  to  the  eye,  and  more  in  harmony 
with  surroundings,  and  which  are  the  least  susceptible  to  change  by  the 
chemical  action  of  the  secretions. 

Odor  and  taste  are  possessed  by  most  metals 
Odor  and  taste.  to  such  an  infinitesimal  extent  that  it  is  almost  un- 
necessary .to  mention  them.  Copper  and  zinc, 
however,  have  the  most  definite  metallic  odor  and  taste,  but  as  this  is 
apparent  only  when  they  are  subjected  to  a  temperature  higher  than 
that  of  the  body,  and  they  are  used  only  for  the  purpose  of  alloying,  the 
characteristic  is  of  no  especial  importance. 

All  metals  are  capable  of  being  reduced  to  a 
Tuslbility.  liquid   state   under   the   influence   of   heat,   but   the 

melting  point  or  degree  of  fusibility  differs  greatly, 
and,  like  the  color,  is  modified  by  alloying.  The  practical  infusibility 
of  platinum  of  any  thickness  greatly  facilitates  some  classes  of  work, 
and  the  controlling  at  will  of  the  fusing  point  of  gold  by  alloying  makes 
the  assemblage  of  innumerable  parts  and  the  art  of  soldering  a  com- 
parati\-ely  easy  and  simple  matter. 

Malleability  is  the  inherent  property  of  a  metal 
malleabHity.  which  admits  of  its  being  hammered  or  rolled  into 

thin  sheets  wthout  destroying  the  continuity  of  its 
surface,  and  permits  of  its  easy  manij:)ulation  and  ada])tation. 

Ductility  is  the  proj^erty  which  admits  of  being 
Ductility.  drawn  out  into  lengths  of  a  small  diameter,  such  as 

wire, 


13 

Tenacity  is  tlie  property  of  molecular  resistance 

tenacity.  to  tension,  upon  which  depends  the  strength  of  the 

metal. 

In    studying   the    accompanying   table,    it    Avill    1)C    noted    that    gold. 

while   ranking  first   of  the   five   principal   metals  most   commonly   used, 

in  malleability  and  ductility,  ranks  last  in  tenacity,  but  this,  of  course, 

refers  to  pure  gold,  the  tensile  strength  of  which  is  greatly   increased 

by  alloying  with  copper,  silver  or  platinum. 

Malleability.  Ductility.  Tenacity. 

Rank  I.       Gold.  Gold.  Iron. 

"      II.     Silver.  Silver.  Copper. 

"      III.  Copper.  Platinum.  Platinum. 

"      IV.  Platinum.  Iron.  Silver. 

"      V.     Iron.  Copper.  Gold. 

PbV^ical  Processes. 

The  physical  processes  which  mostly  concern  the  dentist  in  the 
manipulation  of  the  metals  to  accomplish  the  necessary  and  desired 
physical  changes  are  those  of  soldering,  welding,  annealing,  tempering, 
and  alloying,  and  a  clear  conception  of  each  is  of  infinite  importance 
in  their  use. 

Soldering  is  the  process  of  uniting  surfaces  of 
Soldering.  metal  by  fusion  or  superficial  alloying. 

Welding  is  the  process  of  uniting  surfaces  of 
melding.  metal  by  molecular  attraction  under  heat  and  pres- 

sure. 

Annealing  is  the  process  of  softening  or  secur- 

Jlnnealing.  ing  increasd  malleability,  and  as  all  metals  expand 

under  the  influence  of  heat,  they  in  turn  become 

softened  because  of  the  separation  of  the   molecules  produced  by  this 

expansion. 

To  accomplish  this,  they  should  be  slowly  heated  to  a  cherry-red 
and  allowed  to  cool  gradually,  though  plunging  gold  into  water  or 
alcohol  does  not  interfere  with,  and  the  latter  seems  to  even  increase 
its  softness,  while  aluminum,  fusing  at  a  cherry-red  heat,  is  best  annealed 
by  coating  each  surface  v.'ith  oil.  then  igniting  same  and  allowing  it  to 

burn  ofif.  „  .        .       ,  r   ,       ,     ■ 

lempermg   is   the   process   of   hardenmg.      In 

tempering.  gold,  platinum,  silver,  copper,  etc.,  it  obtains  as  the 

result  of  manipulation  and  C(MTSccutive  working,  due 
to  a  molecular  condensation;  while  in  iron  containing  carbon  (steel)  sud- 
den thermal  changes  from  various  degrees  of  heat  produce  hardness  in 


Temperatu 

re. 

Color. 

430  to  450 

Fah. 

Light  yellow. 

470  Fah. 

Med. 

490  Fah. 

Brown     " 

510  Fah. 

"        purpl 

520  Fah. 

Purple. 

530  to  570 

Fah. 

Blue. 

14 

proportion  to  the  quantity  of  carbon  present,  and  the  manner  and 
method  of  cooling;  while  in  some  alloys  the  reverse  condition  obtains. 
The  accompanying  table  is  indicative  of  the  heat  and  color  neces- 
sary in  tempering  the  various  kinds  of  instruments  used.  (Essig:  Am. 
Text  book,  Pros.  Dent.,  p.  131.) 

Use. 
Enamel  chisels. 
Excavators. 
Pluggers. 
Saws,  etc. 

Wood-cutting  tools. 
Clamps,    etc.,    when    elas- 
ticity is  desired. 

As  alloys  are  a  combination  of  two  or  more 
JRIIoyiilg*  metals,  alloying  is,  of  course,  the  process  of  com- 

bining metals,  and  is  of  material  significance  be- 
cause so  few  are  now  used  in  their  pure  state.  Most  metals  enter  freely 
into  combination  with  others,  the  alloy  resulting  frequently  possessing 
characteristics  entirely  different  from  those  of  any  one  of  the  component 
parts. 

They  always  fuse  lower  than  the  highest  fusing,  and  often  lower 
than  the  most  easily  fusible,  and  in  compounding  them  the  least  fusible 
should  usually  be  melted  first  in  a  clean  crucible,  and  the  others  added 
in  relation  to  and  in  accordance  with  their  fusibility,  after  first  carefully 
weighing  out  the  proper  proportions. 

Alloys  of  gold,  copper  and  silver  can  be  melted  and  incorporated 
almost  simultaneously  with  comparative  ease,  while  those  containing 
platinum  or  zinc  are  more  difficult.  The  former  is  usually  added  by 
feeding  it  into  the  molten  mass  in  thin,  ribbon  or  foil  form,  while  the 
latter  is  best  incorporated  in  the  shape  of  brass  or  some  other  alloy  of 
known  formula,  because  of  the  rapid  volatihzation  of  the  metal.  When 
zinc  is  to  be  added  in  the  pure  state,  the  proper  quantity  should  be 
weighed,  broken  into  small  pieces  and  each  piece  coated  with  a  film  of 
paraffin  or  wax,  then  quickly  carried  into  the  mo''_n  mass  with  pliers. 

In  this  work  it  is  necessary  that  one  should  be  familiar  with  the 
table  of  weight  used  for  the  purpose. 

Troy  Weight.  ■" 

24  grains   (gr.)  ==  i   pennyweight  (dwt.). 

20  pennyweight   (dwt.)      ==  i  ounce   (oz.). 
12  ounces   foz.)  =  i  pound   (lb.). 


15 


Scale. 

lb. 

oz.      dvvt.       gr. 

I  = 

=  12  =  240  =  5760 

I  =    20  =    480 

I  =    24 

Consideration  of  tbc  metals. 

The    color,    malleability,    compatibility,    slight 
gold.  susceptibility    to    the    chemical    influences    of    the 

secretions  and  other  qualities  possessed  by  gold 
make  it  easily  the  nearest  approach  to  the  ideal  for  universal  use,  and 
while  the  higher  artistic  and  esthetic  tendency  should  always  be  to 
avoid  its  conspicuous  display  in  the  mouth  as  much  as  possible,  its 
sphere  of  usefulness  is  unlimited. 

Owing  to  its  extreme  softness  in  the  pure  or  unalloyed  state,  how- 
ever, it  must  be  combined  with  other  metals  which  will  impart,  to  a 
desired  degree,  the  stifitness  and  strength  necessary  to  withstand  the 
stress  and  wear  imposed,  without  appreciably  affecting  its  other  quali- 
ties, and  the  ease  with  which  it  may  be  thus  alloyed  greatly  enhances 
its  value. 

In  prosthetics  the  use  of  gold  in  the  pure  form  is  necessarily  lim- 
ited, being  usually  confined  to  work  where  a  perfect  adaptation  is  in- 
dicated, such  as  backings  for  porcelain  facings,  individual  bands,  etc., 
where  it  is  to  be  afterward  reinforced,  and  also  as  a  solder  for  platinum 
work. 

In  alloying  gold  the  term  karat  is  applied  to 
l^arat.  the  degree  of  fineness,  and  designates  the  propor- 

tion of  pure  gold  to  the  ratio  of  24  parts.  Thus 
24  K.  is  virgin  pure,  while  18  K.  is  composed  of  18  parts  of  gold  and  6 
of  alloy. 

Platinum    is    rapidly    acquiring    an    extensive 
Platinum.  sphere  of  usefulness  in  dental  art,  and  because  of 

its  many  admirable  physical  properties  is  second 
only  to  gold.  Those  of  malleability  and  practical  infusibility  render  its 
manipulation  more  or  less  easy,  and  have  made  possible  the  success  of 
porcelain  work  in  the  various  phases  of  its  present  application;  and  it 
withstands  the  chemical  action  of  the  secretions  so  much  better  than 
gold  as  to  rank  first  in  compatibility  with  the  tissues,  which  take  most 
kindly  to  it.  It  is  also  used  extensively  in  alloying  gold  to  which  it  im- 
parts special  properties. 


i6 

The   use   of    iridium,    the   physical    properties 

Tridiutn.  of  which   resemble,   but  are  more   refractory  than 

platinum,    is   confined   to   alloying   with    the   latter, 

the  combination  forming  a  tougher,  harder  metal,  such  as  is   indicated 

in  post  material   for  dowel  crowns  and   other  instances  requiring  more 

than  ordinary  strength. 

For  the  purpose  of  reducing  the  fineness  and 
Alloys  of  6old.  increasing  the  strength  of  gold,  copper  and  silver 

are  mainly  used  as  the  alloy,  usually  in  the  propor- 
tion of  two  parts  of  copper  to  one  of  silver.  The  former  imparts  hardness 
and  elasticity,  and  the  latter  pliability  and  strength,  together  with  a 
preservation  of  the  original  color  which  copper  alone  would  change, 
except  where  the  desired  fineness  of  the  gold  after  alloying  would  not 
admit  of  sufficient  proportions  of  same  to  possess  the  requisite 
strength,  when  platinum  is  added  in  small  proportions  to  secure  this 
result. 

For  crown  and  bridge  work,  where  strength  and  good  color  should 
be  combined  and  are  prerequisites,  the  gold  most  generally  used  to  the 
best  advantage  is  of  about  22  K.  fineness,  which  is  necessary  to  resist 
or  secure  immunity  from  the  chemical  action  of  the  secretions,  retain 
its  color  and  luster  and  withstand  the  stress ;  and  is  used  in  plate  vary- 
ing from  28  to  30  U.  S.  Standard  Gauge. 

The  following  are  three  common  formulee  used  for  this  purpose: 

No.  I.        22  K.  No.  2.  21.6  K.  No.  3.       21.6  K. 

Pure  gold,       22  dwt.   Pure  gold,  90  parts.    Coin  gold,     50  parts. 

"      copper,     I      "  "      copper,       5      "         Pure      "        45      " 

"      silver,      18  gr.  "      silver,         5      "  "     silver,     5      " 

Platinum,  6  gr. 

The  United   States  coinage,  gold,  90;  copper, 
Coin  Gold.  TO,  was   for  many  years  the  means  of   furnishing 

plate  which  was  used  exclusively,  but  wdiich  is  not 
employed  so  extensively  now  because  of  the  extreme  hardness  of  gold 
alloyed  with  copper  alone,  and  of  the  objectionable  reddish  color,  which 
is  not  so  pleasing  to  the  eye,  especially  when  contrasted  by  proximity 
with  the  bright  yellow  of  a  pure  gold  filling.  It  may  be  used  to  good 
advantage,  however,  in  combination  with  pure  gold  and  silver  in  proper 
proportions,  because  of  the  definite  knowledge  of  the  proportion  of 
copper  contained. 


17 

Gold  and  platinum  alloy  is  indicated  wherever 

Gold  additional  strength  and  springy  elasticity  are  desired, 

and  Platinum.  such  as  clasps,  and  for  stiffening  the  work  over  parts 

which    will    be    subjected    to    more    than    ordinary 

stress,  which  property  the  addition  of  platinum,  one  part  in  24,  imparts 

to  the  alloy.     The   following   formula   is   used   for   the   purpose : 

Pure  gold,  20  parts. 
Pure  copper,  2      " 

Pure  silver,  i  part. 

Platinum,  i     " 

Platinized  gold  is  a  form  of  plate  made  by  fus- 
PlatiniZCd  Gold.  '"g  Pi^^re  gold  over  one  surface  of  platinum,  which 
upon  being  passed  through  the  rollers  then  presents 
a  smooth,  unbroken  surface  of  each  metal.  It  is  much  used  in  gold 
work  where  infusibility  seems  desirable,  and  the  presentation  of  a  sur- 
face of  gold  preferable  to  that  of  platinum.  It  is  also  frequently  useful 
as  a  backing  for  porcelain  facings  because  of  the  advantage  of  control- 
ling or  preserving  the  color  by  placing  next  to  the  porcelain  whichever 
surface  may  cause  the  least,  or  produce  the  most  desirable  change. 

Solders. 

The  advent  of  porcelain  work  and  the  use  of 

Platinum  Solder.        liigh    fusing    "bodies"    has    created    a    demand    for 

a  solder  more  infusible  than  pure  gold,  which  was 

previously  used   for  the   purpose,   in  order  that  joints  so  made   would 

not  be  affected  by  the  high  degree  of  heat  necessary  to  fuse  or  vitrify 

the  body. 

If  there  is  absolute  contact  of  the  parts  to  be  united,  pure  gold  can 
be  successfully  used,  because  if  thoroughly  and  sufficiently  fused,  it  be- 
comes an  integral  part  of  the  platinum  by  alloying  with  it;  but  in  ex- 
tensive work  platinum  solders  are  an  advantage  because  of  overcoming 
the  possibility  of  a  change  in  the  relation  of  the  parts,  caused  by  the 
shrinkage  of  the  porcelain,  which  is  considerable. 

Such  solders  are  now  prepared  for  the  purpose,  ranging  from  10 
to  40  per  cent  of  platinum  in  combination  with  gold,  but  less  than  20 
per  cent  is  of  no  advantage,  and  more  than  25  per  cent  is  unnecessary. 
They  may  be  easily  compounded  by  thoroughly  fusing  the  gold  and  then 
feeding  into  the  molten  mass  the  desired  proportion  of  platinum  in  foil 
or  ribbon  form,  after  which  it  should  be  hammered  out  and  remelted 
several  times  to  insure  a  thorough  admixture. 


i8 

Gold  solders  are  alloys  of  gold  so  compounded 
Gold  Solders.  as  to  fuse  slightly  lower  than  plate  of  the  same  fine- 

ness or  karat;  should  be  composed  of  the  same 
metals  to  preserve  a  close  resemblance  in  color,  and  differ  only  in  the 
incorporation  of  a  metal  which  will  reduce  the  fusing  point  and  impart 
flowing  properties.  Thus  a  20  K.  solder,  for  instance,  should  fuse  read- 
ily on  plate  of  the  same  K.,  otherwise  it  would  not  be  a  solder  in  the 
sense  of  the  meaning. 

Zinc  is  mostly  used  for  the  purpose  of  reducing  the  fusibility  and 
imparting  the  requisite  flowing  properties,  but  should  not  be  in  pro- 
portion more  than  1^2  to  2  parts  in  24;  because  if  in  greater  quantity 
the  alloy  would  be  rendered  brittle,  the  strength  thus  diminished,  and 
the  susceptibility  to  chemical  influences  when  exposed  to  the  action  of 
the  secretions  increased.  Solder  of  a  lower  K.  than  is  absolutely  neces- 
sary should  never  be  used,  because  the  lower  the  K.,  the  greater  the 
affinity  for  oxidation  and  the  susceptibility  to  chemical  action ;  and  in 
consequence  the  seam  of  union  and  the  surface  exposed  are  always 
rendered  more  or  less  conspicuous ;  hence  it  is  desirable  to  begin  with  as 
high  a  karat  as  possible,  so  that  subsequent  solderings  may  be  made 
with  those  of  a  degree  of  fineness  which  will  aid  in  precluding  this  ten- 
dency. And  as  the  grades  which  are  prepared  for  our  use  invariably 
run  lower  than  the  karat  stamp  upon  them,  those  of  so-called  16  and 
14  karat  have  but  a  very  limited  sphere  of  usefulness. 

The  following  formulas  give  the  average  composition  of  the  vari- 
ous grades  of  dental  solders : 

22  K.  Solder. 
Pure     gold,  22  dwt. 

Brass,  2     " 

Coin  Solder. 
Coin  gold,  5  dwt. 

Brass,  i 

20  K.   Solder. 
Pure  gold,  20  dwt. 

Dorrance's  alloy,       4     " 

14  K.  Solder. 

Pure  gold,  14  dwt. 

"      silver,  5  " 

"      copper,  3  "        12  gr. 

"      zinc,  I  "        12  gr. 


18  K. 

Soldei 

Pure  gold. 

18  dwt. 

"      silver, 

3     " 

"      copper. 

I     " 

Brass, 

2     " 

16  K. 

Solder. 

Pure  gold. 

II  dwt., 

12 

gr. 

"      silver, 

3     " 

"      copper. 

I     " 

12 

gr. 

"      zincy 

12 

gr. 

19 

As  most  of  the  scrap  gold  must  of  necessity 
Sompounding  Solders,  be  of  uniform  karat  or  degree  of  fineness  for  the 
reasons  previously  mentioned,  and  because  of  the 
ease  of  securing  the  various  karats  of  plate  and  solder  by  the  dentist, 
it  is  scarcely  necessary  to  observe  or  be  familiar  with  the  method  of 
ascertaining  and  computing  the  fineness  of  gold  to  any  extent,  but  as 
it  may  often  be  desirable  to  compound  solders  it  is  well  to  know  the 
method  of  reducing  scrap  to  the  various  karats  used. 

The   following   simple   rule   will   enable   anyone   to   reduce   a  given 
quality  of  scrap  to  any  desired  fineness  of  solder. 

]\Iultiply  the  weight  of  gold  by  the  karat  and 
|^Ul{,  divide  by  the  desired  karat.    The  difference  between 

the  answer  after  dividing,  and  the  original  quantity 
of  gold,  is  the  quantity  of  alloy  necessary  to  be  added. 

P  Reduce  4  dwt.,   3  gr.,  22   K.   gold  to   18  K. 

solder. 
4  dwt.  -f-  3  gr.   (original  quantity)  =  gr.  99. 
99  X  22  (original  karat)  =  2178. 
2178  H-  18  (desired  karat)  =  121. 
121  — 99  (dif.  bet.  result  and  orig.  quantity)  =:  22. 
Ans. :    22  gr.  of  alloy  should  be  added. 
For  this  purpose  the  alloy  should  of  course  contain  copper,  silver 
and  zinc,  and  may  be  secured  in  the  most  convenient  form  in  the  shape 
of  known  formulae,  such  as  brass,  Dorrance's  alloy,  or  silver  solder. 

Brass  is  composed  of  copper  and  zinc  in  pro- 
Bfa$$.  portions    suitable    for    the    purpose    intended,    us- 

ually varying  from  equal  parts  of  each  to  70  of  cop- 
per and  30  of  zinc,  and  owing  to  its  close  resemblance  to  gold  in  physical 
properties  and  characteristics  is  much  used  in  various  lines  of  work. 
When  used  as  an  alloy  for  gold  in  compounding  solders,  its  definite 
formula  should  of  course  be  ascertained,  and  that  composed  of  copper 
50,  zinc  50,  is  the  best  for  the  purpose. 

Dorrance's  alloy,  suggested  by  Dr.  W.  H.  Dor- 
Dorrancc'S  Jllloy.        ranee,  is  used  extensively  in  reducing  gold  to  solders, 
being  a  combination  of  the  three  principal  metals 
used,  in  good  proportions,  with  copper  in  the  preponderance.     The  fol- 
lowing is  the  formula : 

Copper,  6  parts. 
Silver,     2      " 
Zinc,       4      " 


20 

Silver  solder  is  an  alloy  of  copper,  silver  and 

Silver  Solder.  zinc,  with  silver  in  the  greatest  proportion,  and  is 

much  used  in  the  making  of  gold  solders,  as  the 

alloy,  as  well  as  being  an  economical  hard  solder  for  various  lines  of  work 

where  brass  and  German  silver  are  used.     A  common  formula  is: 

Silver,     6  parts. 
Copper,  3      " 
Zinc,        I  part. 

German  silver  is  used  to  some  extent  in  tempo- 
Gcrman  Silver.  rary  work  of  all  kinds,  such  as  dowels  for  temporary 

crowns  and  bands   for  matrices,   etc.     It  is  com- 
posed of  copper  and  zinc,  with  the  addition  of  nickel,  which  increases 
the  fusing  point  and  gives  a  harder,  tougher  alloy. 
The  following  formula  is  much  used: 

Copper,  50  parts. 
Zinc,        30      " 
Nickel,    20      " 

Fusible  alloys  are  those  in  which  the  lower  fus- 
Tuslble  Jllloys.  ing  metals  are  combined,  such  as  lead,  tin,  bismuth, 

antimony,  and  cadmium,  and  are  intended  for  use 
in  making  dies  and  counterdies  for  swaging  in  crown-work,  and  for  the 
purpose  of  obtaining  models  direct  from  plaster  impressions,  or  from 
the  mouldine  compounds  suggested  by  Dr.  George  W.  Mellotte,  and 
composed  of  potter's  clay  and  glycerine.  The  extreme  fusibility  of 
these  alloys  depends  to  a  great  extent  upon  the  proportion  of  bismuth 
incorporated,  and  varies  accordingly.  The  following  are  formulae  of 
the  various  known  alloys  of  this  nature : 

Newton's  Alloy. 
Bismuth,  8 

Lead,  5 

Tin,  3 

Fusing  point,  200°  F. 
F. 

Hodgen's  Alloy. 

Bismuth,  8 

Lead,  5 

Tin,  3 

F.  Antimony,        2 

Fusing  point,  224°  F. 


Wood's 

Alloy. 

Bismuth, 

5 

Lead, 

4 

Tin, 

2 

Cadmium, 

I 

Fusing  point. 

140 

Rose's 

Alloy. 

Bismuth, 

8 

Lead, 

8 

Tin, 

3 

Fusing  point. 

174' 

21 

Mellotte's  Alloy.  Ordinary  Formula. 

Bismuth,  8  Lead,  i 

Tin,  5  Tin,  i 

Lead,  3  Bismuth,  2 

Fusing  point,  200°  F. 

R.  C.  Brophy's  Alloy.  Grouse's  Alloy. 

Bismuth,  3  Bismuth,  8 

Lead,  2^  Lead,  5 

Tin,  25^  Tin,  5 

Fusing  point,  240°  F.  Cadmium,         i 

Fusing  point,  190°  F. 

Molyneaux's  Alloy. 
Lead,  3 

Tin,  2 

Cadmium,  2 

Bismuth,  5 

Fusing  point,  140°  F. 

The  lower  fusing  of  these  various  well-known  alloys  may  be  cast 
directly  into  plaster,  gutta  percha  or  modeling  compound  impressions, 
without  waiting  for  them  to  dry  out,  and  Dr.  Grant  Molyneaux  recom- 
mends that  such  impressions  should  be  dipped  in  water  just  before 
pouring  with  his  alloy  to  secure  the  best  results. 

While  there  is  probably  but  a  very  limited  use 

Soft  Solder.  for  soft  solder,  it  may  sometimes  be  indicated  in 

temporary  work.     The  ordinary  tinner's  solder  is 

composed  of  equal  parts  of  tin  and  lead,  though  any  of  the  fusible  alloys 

will  answer  the  purpose  equally  as  well. 

It  frequently  occurs  that  the  accumulation  of 
Kefilting  6old.  scrap  gold  in  the  laboratory  may  become  so  con- 

taminated with  base  metals,  from  contact  and  from 
the  file,  that  it  could  not  well  be  used  over  again  by  melting  and  rolling 
into  plate,  which  convenience  sometimes  requires,  without  being  first 
subjected  to  some  simple  process  of  refining. 

When  the  scrap  is  composed  mostly  of  a  known  degree  of  fineness, 
this  may  be  quite  easily  accomplished  without  resorting  to  the  chemical 
process,  by  what  is  known  as  the  roasting  method. 

This  consists  of  placing  the  scrap  in  a  clean  crucible  with  plenty 
of  borax,  and  applying  heat  until  a  perfect  fusion  is  reached,  when 
small  pieces  of  potassium  nitrate  (saltpetre)  should  be  consecutively 
added. 


22 


This  oxidizing  agent  furnishes  usually  sufficient  oxygen  to  oxidize 
all  base  metals,  which  oxides  are  absorbed  by  the  borax,  and  if  kept 
up  long  enough  will  result  in  so  materially  refining  the  gold  as  to  per- 
mit of  its  being  annealed,  rolled  to  the  desired  thickness  and  used  over 
again. 

Recovering  and  Refinind  Uldste  Gold. 

While  it  is  very  probable  that  the  average  dentist  will  have  neither 
the  time,  inclination  nor  facilities  for  recovering  the  waste  gold  which 
daily  finds  lodgment  in,  or  becomes  attached  to,  sweepings,  rugs,  carpets, 
disks,  strips,  etc.,  yet  the  method  usually  employed  in  obtaining  and  re- 
fining it  may  be  of  some  general  interest. 

The  sweepings  and  such  various  articles  as  may  contain  gold  are 
first  placed  in  a  suitable  vessel,  and  subjected  to  a  degree  of  heat  in  a  blast 
furnace  which  will  reduce  them  to  ashes  and  residue,  after  which  this 
latter  is  then  finely  pozvdered. 

The  gold,  together  with  its  impurities,  can  now  be  separated  from 
most  of  the  ash,  carbon,  sand,  etc.,  by  a  mechanical  process  of  washing, 
in  which,  because  of  the  high  specific  gravity  of  the  metallic  masses,  the 
latter  will  seek  the  lowest  point,  allowing  the  residue  to  remain  on 
top. 

The  gold  may  now  be  extracted  from  the  remaining  mixture  of 
heavy  material  by  the  following  method :  Treat  with  nitro-hydrochloric 
acid  (aqua  regia),  heat  gently,  agitate  occasionally,  and  then  allow  the 
mixture  to  stand  for  a  few  hours. 

The  solution  is  now  evaporated  until  all  free  acid  has  been  expelled, 
when  it  is  allowed  to  cool,  and  alcohol  and  potassium  chloride  are  added, 
which  precipitates  any  platinum  that  may  be  present. 

The  gold  may  now  be  precipitated  from  the  filtered  solution  by  add- 
ing ferrous  sulphate,  c.p.,  or  heating  it  with  a  solution  of  oxalic  acid, 
when  the  precipitate,  a  fine  brOwn  powder,  should  be  washed  with  dis- 
tilled water,  placed  in  a  graphite  crucible  and  thoroughly  fused  with 
potassium  nitrate  (saltpetre),  or  borax,  as  previously  indicated. 

The  molten  metal  may  be  then  poured  from  the  crucible  into  a  pre- 
viously warmed  and  oiled  mould,  when  an  ingot  of  pure  gold  is  obtained, 
which  may  be  alloyed,  if  desired,  and  rolled  out  to  suitable  thickness 
for  use.* 


*Thft  foreeoini;  is  intendetj  only  as  the  essence  nf  dental  metallnrcry.  tinctured  with  practi- 
cal application  in  its  relation  to  frown  and  hrldfjework.  Tin-  Author  has  quoted  freely  from 
Mitchell's  Dental  Chetnisfrv.Hodaen'^  Dental  Metalliirv.  and  the  American  Textbook  of  Prosthetic 
Deiriisfrv.  edited  by  Dr.  C.  J.  Essig,  and  is  indebted  to  Dr.  J.  P.  Buckley,  of  Chicago,  for  sug- 
gestions and  assistance 


Soldering. 

CHAPTER  III. 

Essential  Requirements:  Cleanliness;  Aeid  Bath.     Flux;  Borax;  Method  of  Using. 
Parr's   Fluxed   Wax,    Liquid    Soldering   Fluids.      Apposition;    Requirements 
and    Method  of   Obtaining.     Uniform   Heat;   Application   and   Require- 
ments.     Difficulties    Encountered :    "Balling   Up,"    Shrinkage,    Base 
Metals,  Gravity,  Fracturing  Porcelain  Facings,  Soldering  Block 
Teeth.    Manipulation  :  Soldering  Without  Investment.    Flame 
Blow-pipes.      Soldering   With   Investment,   Gold    Solder- 
ing, Pure  Gold  Soldering,  Platinum  Soldering,  Oxy- 
Hydrogen   Blow-pipe,   Cooling  After   Soldering, 
To  Prevent  Unsoldering.     Sweating  Process. 
Autogenous  Soldering.     Soft  Soldering. 


In  its  application  to  dentistry  soldering  has  rapidly  assumed  the 
significance  of  an  art  of  much  greater  importance  than  ever  attained 
by  those  presupposed  past  masters — the  gold  and  silversmiths.  This  is 
readily  proven  by  the  ease  with  which  the  process  is  now  executed  in 
the  consecutive  union  of  a  multiplicity  of  parts  and  the  building  or 
restoration  of  contour,  as  compared  with  the  work  along  similar  lines 
confined  to  their  province. 

The  ease  and  dexterity  with  which  such  results  may  now  be  ob- 
tained by  the  more  skilful,  however,  compared  with  the  expressions  of 
doubt  and  even  dread  manifested  by  others,  followed  by  such  discourag- 
ing failures  as  the  burning  or  fusing  of  the  parts,  or  the  fracturing  of 
porcelain  facings,  leads  to  the  very  natural  conclusion  that  in  such 
instances  the  lesson  has  not  been  properly  learned,  and  that  the  subject 
merits  and  demands  more  thoughtful  consideration  and  study,  and  more 
persevering  application  than  is  usually  accorded. 

To  this  end  the  dentist  cannot  too  closely  apply  himself  in  the  eflfort 
to  become  sufficiently  skilled  as  to  render  the  procedure  one  of  simplicity 
and  ease,  together  with  reducing  to  a  minimum,  or  eliminating,  all  attend- 
ing  dangers   of   and   liability   to,   accident,    which    in   this,   the   physical 


24 

process  of  uniting  surfaces  of  metal  by  fusion  or  superficial  alloying, 
will  invariably  follow  a  comprehensive  knowledge  of  the  fundamental 
requirements,  and  a  close  observation  of  all  of  the  essentials  concomitant 
with  success. 

Essential  Kcquiremcnts. 

These  important  considerations  are  cleanliness,  flux,  apposition, 
and  uniform  heat,  and  unless  clearly  understood  from  a  practical  stand- 
point, the  process  involved,  while  perhaps  sometimes  successfully  ac- 
complished, is  necessarily  followed  in  a  more  or  less  perfunctory  manner, 
in  which  case  the  operator  becomes  simply  an  automaton. 

The  thorough  removal  of  all  oxidation  and  de- 

0lcanlinc$$.  posits  of   foreign  nature  from  the  surfaces  to  be 

united  is  highly  necessary  in  order  that  the  solder 

may  become  thoroughly  attached  or  incorporated,  so  that  the  element  of 

strength  may  be  insured  in  the  union.     This  may  be  secured  by  scraping 

or  filing  the  surfaces,  or  by  treating  them  with  an  acid  solution. 

For    this    purpose    sidphuric    or    hydrochloric 
JlCid  Batb.  acid,  diluted  with  an  equal  proportion  of  water,  is 

used,  into  which  the  parts  are  immersed  for  a  few 
moments  to  dissolve  and  remove  all  foreign  substances. 

Sulphuric  acid  is  preferable,  and  for  large  work 
Sand  Batb.  should  be  contained  in  a  porcelain  evaporating  dish 

of  proper  dimensions,  as  heat  materially  increases 
its  cleansing  properties.  The  dish  should  then  be  placed  in  a  shallow 
sheet  iron  bowl  partially  filled  with  sand  and  placed  upon  a  tripod  over 
an  alcohol  or  Bunsen  flame,  by  which  means  the  parts  may  be  boiled,  if 
necessary.  As  the  fumes  thus  given  off  are  more  or  less  injurious  when 
inhaled,  some  provision  must  be  made  for  carrying  them  away,  which 
may  be  quite  easily  accomplished  by  attaching  a  hood  to  a  gas  pipe  and 
permitting  the  latter  to  pass  through  a  hole  in  the  window  at  some  acces- 
sible point  (Fig.   17). 

For  small  work  a  much  more  convenient  method  is  to  freshly  mix 
the  solution  each  time  by  pourincj  into  a  small  quantity  of  acid  an  equal 
proportion  of  warm  water,  when  the  chemical  reaction  will  generate  heat 
enough  to  thoroughly  clean  the  parts,  after  which  it  may  be  thrown  out. 
For  metal  work  only,  where  no  porcelain  is  used,  this  solution  may 
be  saved  by  placing  it  in  a  large-mouthed  bottle  and  used  indefinitely 
and  effectively  when  cold  by  first  heating  the  parts  to  be  cleaned  and 
then  plunging  them  into  the  acid. 


25 

After  removing  the   work  from  the  bath,  it  must  always  be  thor- 
oughly washed  in  clean  water  to  sq  dilute  the  acid  as  to  remove  all  traces 


Fiq.17. 


of  it  before  heating  in  the  flame,  because  if  this  is  not  carefully  done,  and 
any  traces  of  acid  should  remain,  the  formation  of  the  salts  of  the  baser 
metals  which  is  facilitated  by  the  heat  will  at  once  preclude  the  possibil- 
ity of  soldering  until  again  treated  with  acid  and  this  precaution  observed. 


Tlux. 

As  the  affinity  for  absorbing  oxygen  from  the  atmosphere,  which 
nearly  all  metals  possess,  is  increased  by  heat,  the  application  of  it  inci- 
dent to  the  process  of  soldering  causes  the  exposed  surfaces  to  become 
rapidly  oxidized,  in  consequence  of  which  it  is  necessary  to  preclude  the 
possibility  of  such  tendency  and  preserve  the  cleanliness  of  the  parts  in 
order  that  the  solder  may  not  be  prevented  from  readily  fusing  and  be- 
coming alloyed. 

Substances  are  used  for  this  purpose  which,  when  fused  over  such 
surfaces,  keep  them  clean  and  free  of  oxidization,  and  aid  in  the  fusing 
and  alloying.  It  is  equally  necessary  that  the  solder  as  well  as  the  sur- 
faces of  metal  be  thus  treated,  because,  being  a  lower  grade  alloy,  it  is 
more  easily  oxidized.  When  not  so  treated  the  neglect  may  not  infre- 
quently be  the  cause  of  much  obstinacy  in  fusing,  demanding  a  greater 
degree  of  heat  than  otherwise  necessary. 


26 


Borax  is  most  generally  used  for  this  purpose 
Borax.  and  meets  the  ^requirements   in  every  respect,  but 

the  common  practice  of  using  it  in  dry  powdered 
form,  in  far  greater  quantities  than  necessary,  is  to  be  most  vigorously 
condemned,  because  when  first  heated  it  expands  to  such  extent  as  to  not 
infrequently  split  the  investment  and  change  the  relation  of  the  parts; 
may  even  flake  or  deface  the  porcelain  if  it  should  come  in  contact  with  it 
by  fusing  upon  it;  always  displaces  the  solder,  and  usually  results  in  the 
presentation  of  a  pitted  surface. 

To  prevent  this  and  secure  the  best  results,  it  should  be  mixed  with 
clean  water  to  the  consistency  of  a  thin  paste,  and  applied,  before  heating 
the  parts,  with  a  small  camel's  hair  brush,  which  admits  of  its  application 
to  the  particular  surfaces  in  the  proper  and  necessary  quantity. 

Owing  to  the  tendency  to  crystalize,  however,  it  is  difficult  to  pre- 
serve  such   consistency,   but   this   may  be   facilitated   by   preparing  and 


Fiq.18. 


keeping  it  in  a  glass-covered  dish,  where  it  may  be  also  kept  clean  and 
free  from  dirt,  which  is  eminently  desirable.     (Fig.  i8.) 

This  is  a  hard  wax,  containing  an  admixture  of 
Parr's  Tluxcd  max.      borax,   which   is   much  used,   and   is   a  convenient 
form  of  flux,  as  the  wax  burns  out,  leaving  the 
borax  deposited  upon  the  surfaces  in  small  proportions. 

Liquid  soldering  fluid  is  now  being  extensively 
£l()Uid  used  in  dentistry,  and  has  been  by  jewelers  for  a 

Soldering  TlUid.         number  of  years,  and  is  the  best,  cleanest,  most  de- 
sirable and  convenient  flux  for  our  purpose.    It  is  a 
saturated  solution  of  equal  parts  of  borax  and  boric  acid  in  water,  and  can 
be  more  easily  and  readily  applied  with  a  camel's  hair  brush  or  small  piece 
of  wood  in  proper  quantity  to  a  better  advantage  than  any  other. 

In  all  instances,  however,  the  flux  should  be  applied  before  heating 
the  object  to  be  soldered,  in  order  that  it  may  be  placed  in  or  carried  to 
every  portion  and  surface  of  the  metal  upon  which  the  solder  should 
flow  in  securing  union.  This  is  not  always  possible  if  applied  to  the 
heated  case,  in  which  instance  powdered  borax  is  preferable. 


27 

To  facilitate  the  union  between  the  parts,  the  edges  or  surfaces 
should  always  be  in  absolute  contact,  or  as  nearly  so  as  possible,  so  that 
there  may  be  strength  in  the  joint,  and  no  impediment  offered  to  the 
solder  in  flowing  freely  over  the  surfaces  to  be  united. 

In  case  the  proper  relation  necessary  to  be  sustained  will  not  admit 
of  contact,  it  should  then  be  secured  by  filling  in  between  such  edges  or 
surfaces,  thus  bridging  them  over  with  small  pieces  of  the  metal  of 
which  the  work  is  being  constructed.  This  is  usually  best  accomplished 
with  gold  or  platinum  wire  or  plate,  or  some  of  the  foil  or  crystal  golds, 
the  latter  being  preferable  because  of  their  thickness,  which  should  be 
fitted  or  packed  into  place  before  the  case  is  heated, 

ilnifortti  1)cat. 

The  application  and  proper  manipulation  of  heat  in  securing  the  best 
results  is  an  important  feature,  but  because  of  the  under-valuation  or 
over-estimation  of  the  requirements  is  frequently  the  means  of  much 
discouraging  and  unnecessary  labor,  yet  when  properly  applied  with  the 
former  prerequisites  observed,  the  entire  procedure  is  infinitely  simple. 

In  this  connection  it  must  be  remembered  that,  as  the  process  con- 
stitutes the  alloying  of  the  parts,  the  surfaces  to  be  united  must  be  freely 
exposed,  and  then  brought  to  a  degree  of  heat  exceeding,  or  at  least 
equal  to,  the  fusing  point  of  the  solder  before  union  can  obtain. 

Difficulties  Cncountercl 

If  this  degree  of  uniformity  is  not  scrupulously  observed,  and  the 
heat  be  directed  upon  the  solder  before  the  parts  are  equally  and  suf- 
ficiently heated  to  permit  of  alloying,  the  aggravating  annoyance  of  "ball- 
ing up"  is  invariably  the  result. 

This  tendency  of  the  solder  to  assume  globular 

'^Balling  Up."  form   with   more   or   less    obstinate   persistency    is 

due  only  to  the  difference  between  the  size  of  the 
object  to  be  soldered  and  the  relative  degree  of  heat  required  by  it, 
as  compared  with  the  small  quantity  of  solder  used  and  its  consequently 
greater  fusibility.  If  much  time  be  thus  consumed  the  baser  alloy  con- 
tained in  the  latter  may  be  burned  out,  the  loss  or  depletion  of  which  will 
increase  the  fusibility  and  decrease  the  flowing  properties  to  such  extent, 
perhaps,  as  not  infrequently  to  cause  the  melting  of  the  parts. 

As  this  is  obvious,  and  since  the  affinity  of  one  metal  for  combining 
with  another  is  increased  by  heat,  it  is  only  necessary  to  first  raise  the 
temperature   of   the  higher   fusing  parts    equal   or  near  to  the  melting 


28 

point  of  the  most  fusible,  when  very  Httle  further  heat  well  directed  upon 
both  simultaneously  will  result  in  perfect  union  with  little  or  no  effort, 
and  as  the  solder  will  follow  the  heat  or  flow  in  the  direction  of  the  great- 
est degree  of  temperature,  it  can  be  controlled  accordingly. 

As  the  shrinkage  of  solder  increases  in  propor- 
SbrinkagC.  tion  to  the  quantity  of  baser  alloy  incorporated,  and 

manifests  itself  to  such  an  appreciable  extent  in  gold 
work,  it  is  imperative  to  use  the  utmost  precautions  toward  preventing 
the  possible  change  in  the  relation  of  the  parts  which  might  thus  ensue, 
and  which  may  not  infrequently  result  in  jeopardizing  the  fit  and  adap- 
tation. 

To  preclude  this  possibility  it  is  necessary  to  observe  the  require- 
ments of  apposition  and  contact  very  closely,  and  in  more  or  less  exten- 
sive work  it  may  be  further  prevented  by  soldering  each  piece  separately 
first  so  that  in  the  final  assemblage  of  the  parts  as  little  solder  may  be 
used  and  carried  to  the  fluid  state  as  is  immediately  required  to  secure 
union  and  strength.  Thus  very  large  cases  should  be  soldered  in  sections 
and  afterward  united. 

Perhaps  paramount  among  the  difficulties  most 

TractUfIng  of  frequently  experienced  is  the  checking  or  fracturing 

Porcelain  Tacings.       of  porcelain  facings,  but  this,  while  seemingly  and 

apparently  unavoidable,   is   in  nearly  all   instances 

due  to  the  most  flagrant  negligence,  in  so  far  as  soldering  is  concerned. 

In  this  connection  it  is  necessary  to  consider  the  fact  that  a  porce- 
lain facing  constitutes  and  presents  two  distinct  substances,  the  mineral 
and  the  metal — the  porcelain  and  the  pins — each  of  which  possesses  physi- 
cal properties  which  are  affected  very  differently  by  the  heat  to  which 
they  are  subjected. 

The  mineral,  absorbing  heat  very  slowly  and  gradually,  retains  it 
for  a  considerable  length  of  time,  while  the  metal  absorbs  it  readily,  and 
gives  it  off  or  cools  with  equal  rapidity ;  consequently,  in  the  process  of 
soldering,  the  utmost  care  must  be  exercised  in  applying  the  heat  so 
gradually  and  uniformly  from  the  very  outset  that  the  porcelain,  which  is 
a  friable  material,  will  receive  it  either  preceding  or  at  least  simultaneously 
with  the  platinum  i)ins,  in  order  that  the  expansion  which  takes  place 
in  each  may  occur  evenly  and  uniformly.  It  is  invariably  this  uneven 
expansion,  wherein  that  of  the  porcelain  is  not  sufficient  to  accommodate 
that  of  the  pins,  which  causes  the  fractures  occurring  across  the  surface  of 
the  facing,  always  radiating  from  the  pins.  To  various  other  reasons, 
however,  may  sometimes  be  attributed  this  difficulty,  but  the  percentage 
is  very  small  as  compared  with  that  of  uneven  expansion. 


29 

Such  other  cases  may  be  from  impingement  due  to  the  shrinkage  of 
the  solder  and  augmented  by  too  close  proximity  of  parts  with  each  other 
to  accommodate  this  shrinkage,  from  overhanging  edges  of  backings, 
which  in  contracting  necessarily  impinge  upon  the  edges  of  the  facings, 
causing  innumerable  small  checks  along  such  edges ;  to  perforating  the 
backings  with  openings  much  too  large  for  the  reception  of  the  pins, 
thus  permitting  the  solder  to  run  in  between  backing  and  facing;  or  to 
carelessness  in  bending  the  pins  (to  retain  the  backings),  in  such  manner 
as  to  produce  a  constant  strain  on  the  porcelain  immediately  surrounding 
their  attachment.  As  a  proof  that  it  is  either  uneven  expansion  or 
faulty  adaptation  of  the  backing,  it  is  noticeable  that  facings  seldom  if 
ever  check  in  porcelain  work  where  they  are  subjected  to  even  a  much 
higher  degree  of  heat. 

Where  there  has  been  extensive  resorption  of 
Soldering  tissue  it  will  sometimes  be  desirable  to  use  what  are 

Block  known  as  gum  blocks.   Because  of  the  curve  of  these 

Ccctb.  blocks  there  would  be  more  or  less  liability  of  frac- 

ture, even  in  skilful  hands  were  a  single  backing  to 
be  used  for  the  whole  block.  By  a  very  simple  method,  however,  blocks 
of  three  and  even  four  or  more  teeth  may  be  safely  utilized,  thus  avoiding 
the  unsightliness  and  uncleanliness  of  joints  which  would  result  from 
using  single  gum  teeth.  This  absence  of  joints  is  especially  desirable 
when  restoring  the  anterior  upper  teeth,  and  in  replacing  the  four  in- 
cisors a  most  artistic  result  may  often  be  attained  with  a  single  gum 
block.  In  using  these  blocks  each  tooth  in  the  block  should  be  backed 
separately,  the  backings  being  so  placed  that  they  would  not  absolutely 
touch.  In  adapting  the  blocks  to  the  piece  to  which  they  are  to  be  attached' 
care  should  be  employed  to  so  fit  them  that  the  minimum  of  solder  will  be 
required  to  effect  union.  There  will  be  no  danger  of  cracking  the  block 
during  this  last  procedure,  because  the  base  to  which  attachment  is  made 
should  afford  ample  resistance  to  the  slight  shrinkage  of  the  solder  at  the 
bases  of  the  separate  backings. 

Another   not    unusual    occurrence,    during   the 

Base  Ittetals.  process  of  soldering  is  the  appearance  of  small  holes 

or  perforations  on  the  surface  of  the  metal.  These 
are  usually  due  to  the  presence  of  some  of  the  baser  metals,  which  may 
become  attached  by  contact  with  the  dies  in  swaging;  from  a  file  contain- 
ing same,  or  from  the  work  bench,  and  can  only  be  avoided  by  always 
carefully  treating  the  piece  to  an  acid  bath  immediately  preceding  each 
application  of  heat. 


In   extensive    work   it   is   always   desirable   to 
Gravity  observe  the  laws  of  gravity  as  much  as  possible,  for 

while  it  is  true  that  the  solder  will  follow  the  heat, 
and  its  flowing  may  be  so  controlled  in  a  measure,  when  used  in  con- 
siderable proportion  its  weight  will  naturally  cause  it  to  seek  the  lowest 
point,  hence  it  frequently  becomes  necessary,  especially  in  large  cases 
for  the  anterior  part  of  the  mouth,  where  the  curvature  is  greater,  to 
change  the  position  of  the  case  as  the  soldering  progresses  in  order  to 
retain  the  mass  in  the  desired  location  when  in  the  fluid  state. 

manipulation. 

Closely  following  a  consideration  of  the  requirements  and  difficulties 
encountered  in  this  work  is  the  importance  of  practical  manipulation  in 
its  various  phases,  the  proper  execution  of  which  renders  the  procedure 
easy  and  simple. 

In  soldering  bands,  caps,  and  cusps,  where  no 

Soldering  investment  is  necessary  to  sustain  the  relation  of  the 

UlitbOUt  Investment.       parts,  the  work  is  more  easily  accomplished  because 

of  the  greater  opportunities  for  securing  uniformity 

of  heat,  and  can  usually  be  done  in  the  flame  of  an  alcohol  lamp  or  Bunsen 

burner  with  ease;  but  the  manner  of  holding  the  object  in  the  flame,  and 

the  material  of  which  the  instruments  for  the  purpose   are  made  bear 

materially  upon  the  dexterity  and  simplicity  with  which  the  procedure 

may  be  accomplished. 

As  different  parts     of  the   flame  vary  in  the 
Tlamc.  degree  of  intensity  of  heat,  it  is  of  importance  that 

the  object  be  held  in  a  proper  relation  to  the  same 
in  order  that  the  soldering  may  be  more  easily  accomplished.  The  flame 
consists  of  an  outer  sheath  varying  in  color  from  a  dark  blue  at  the  base 
to  a  yellowish  white  at  the  point,  which  envelopes  a  central  cone  of  light 
bluish  color,  at  the  summit  of  which  the  greatest  degree  of  heat  is  present 
(Fig.  19). 

Fine-pointed  pliers  should  invariably  be  used  and  the  object  should 
be  held  at  a  point  as  remote  from  the  surface  to  be  soldered  as  possible, 
so  that  the  pliers  will  not  absorb  the  heat.  Because  of  this  tendency,  steel 
instruments  should  seldom  be  used,  while  those  made  of  nickel,  or  its 
alloy,  or  of  steel  with  fine  platinum  points  answer  the  purpose  much 
better  because  they  absorb  so  little  heat  that  they  may  be  held  comfortably 
in  the  hand. 

In  soldering  platinum  with  pure  gold  the  use  of  flux  is  not  impera- 
tive, for  the  reason  that  both  metals  are  pure  and  devoid  of  alloy,  which 


31 

greatly  diminishes  their  susceptibiHty  to  oxidation,  and  the  ordinary 
mouth  blowpipe  (Fig.  20)  is  all  that  is  necessary;  while  platinum  solder 
up  to  twenty-five  per  cent,  can  be  successfully  used  with  the  "combin- 
ation" blowpipe  and  bellows    (or  compressed  air)    (Fig.  21)   or  may  be 


equally  well  done  with  the  gasoline  blowpipe,  a  successful  and  convenient 
style  of  which  includes  a  burner  and  is  manufactured  by  Dr.  R.  C.  Brophy, 
of  Chicago,  111.  (Fig  22),  or  small  pieces  of  platinum  work  where  the 
contact  and  relation  can  be  sustained  by  proper  adjustment,  and  where 


Fiq.20. 

no  investment   is  necessary,  can  very  often  be  soldered   in  the  electric 
furnace  with  much  convenience. 

Where    the    case    is    necessarily    invested    the 
Soldering  process  is  usually  considered  as  a  somewhat  more 

mitb  Investment.        difficult    and    arduous   task,    which    for   ver}'-   good 
reasons  it  unfortunately  often  proves  to  be,  the  prin- 
cipal one  of  which  is  a  failure  to  properly  and  adequately  heat  the  entire 
case  before  attempting  to  solder. 


32 

It  should  first  always  be  placed  upon  a  Bunsen  or  gasoline  burner 
and  allowed  to  remain  sufficiently  long  to  become  gradually  and  thor- 
oughly heated,  which  may  be  hastened,  if  necessary,  by  applying  and  di- 


Fig.  21 


ncj.22, 

recting  the  heat  with  the  "brush"  flame  from  the  blowpipe,  to  the  under 
surface  in  conjunction  with  the  burner.  Then  when  it  shall  have  reached 
a  temperature  indicated  by  a  red  heat,  the  solder  should  be  consecutively 


33 

applied  in  fairly  good  sized  pieces,  which,  with  the  burner  from  beneath 
to  preserve  a  uniform  heat,  and  a  "pointed"  flame  from  the  blowpipe 
directed  upon  the  parts,  will  easily  and  quickly  accomplish  the  object 
sought  without  useless  expenditure  of  effort  or  energy. 

The  fusing  and  flowing  of  the  solder  in  the  desired  location  and 
direction  may  be  facilitated  by  using  the  point  of  an  ordinary  slate-pencil 
when  in  the  partially  fused  or  plastic  state,  after  which  only  heat  sufficient 
to  solidify  the  mass  until  a  smooth  surface  obtains  should  be  applied. 

In  fusing  gold  solder  of  any  grade  the  require- 
6old  Soldering.  ments  in  the  degree  of  heat  so  far  as  the  blowpipe 
itself  is  concerned  are  generally  greatly  overestim- 
ated. If  the  case  is  first  properly  heated,  the  combination  blowpipe  con- 
trolled by  the  mouth  easily  furnishes  all  that  is  necessary,  and  is  prefer- 
able and  safer,  as  the  danger  attending  the  burning  of  the  parts  is 
always  increased  by  the  use  of  the  bellows,  because  the  control  is  not 
so  perfect. 

To  blow  a  continuous  flame  with  the  mouth  blowpipe  is  a  valuable 
accomplishment  and  can  be  acquired  with  practice  by  nearly  anyone. 

In  platinum  work,  where  the  danger  of  burning 
Pure  is    eliminated,    and   the    requirements    of   heat   are 

Gold  Soldering.  increased  by  the  use  of  pure  gold  as  a  solder,  the 
bellows  will,  of  course,  be  found  convenient  and  use- 
ful, though  even  then  the  skilful  manipulation  of  the  mouth  blowpipe 
will  accomplish  the  work.  However  it  may  be  obtained,  heat  enough 
to  ihorouf/hly  fuse  the  gold  until  it  becomes  alloyed  with  the  platinum, 
so  as  to  occupy  no  apparent  space  except  that  in  the  immediate  joint,  is 
absolutely  essential  to  successful  results  in  this  work. 

In  small  cases  where  a  large  investment  is  not 

Platinum  indicated,   platinum   solders  up  to  twenty-five   per 

Soldering.  cent,  may  be  fused  with  the  bellows  or  compressed 

air,  but  the  necessary  degree  of  heat  to  thoroughly 

and  easily  fuse  them  can,  of  course,  be  best  obtained  from  the  oxy-hydro- 

gen  flame,  which  is  indicated  always  in  extensive  work. 

The  use  of  an  oxy-hydrogen  blowpipe  is  re- 
Oxy-I)ydr09en  garded  by  many  as  being  somewhat  complex  and  ex- 

BlOWpipe.  pensive,  but  is  in  reality  most  simple  and  compara- 

tively inexpensive.  In  manipulating  one  the  illumin- 
ating gas  should  be  turned  on  first  and  ignited,  and  then  the  nitrous  oxide 
valve  opened  very  slowly  and  gradually,  until  perfect  combustion  is  ob- 
tained. The  case  should  be  first  thoroughly  heated  with  the  brush  part  of 
the  flame  after  which  it  is  necessary  to  bring  the  point  of  the  central  cone 


34 

m  contact  with  the  surfaces  to  be  united,  as  this  is  the  heat-producing  por- 
tion.   The  soldering  may  then  be  accomphshed  with  ease. 

The  extreme  heat  and  incandescence,  however,  is  very  trying  to  the 
eyes,  and  a  pair  of  smoked  glasses  will  be  found  most  conducive  to 
success  and  comfort.  Fig.  23  illustrates  a  simple  and  inexpensive  ap- 
paratus for  this  work,  manufactured  by  L.  J.  Mason  &  Co.,  of  Chicago, 
Illinois. 

When  the   soldering  has  been  completed,  the 
Cooling  JlftCl*  case  should  remain  over  the  flame  for  a  few  mo- 

Soldcrins.  ments  to  prevent  too  rapid  cooling  and  the  conse- 

quent sudden  contraction  or  shrinkage,  after  which 
the  flame  may  be  turned  off  and  the  case  allowed  to  stand  until  cool  enough 


nq.23. 

to  handle,  when  it  may  be  then  removed  from  the  investment,  cleaned 
in  acid,  and  finished. 

In  cases  where  an  investment  is  not  indicated 

Co  Prevent  it  is  frequently  desirable  to  observe  some  precau- 

Unsoldcring.  tions  to  avoid  the  unsoldering  or  re-fusing  of  parts 

previously  united,  which  is  usually  accomplished  by 

the  mere  presence  of  the  investment  itself  when  such  is  used.     This  may 

always  be  very  easily  prevented  by  coating  or  treating  such  surfaces  with 

crocus  (ferric  hydrate),  or  a  liquid  solution  of  whiting,  or  plumbago,  in 

water  or  alcohol. 

The  not  infrequent  occurrence  or  presence  of 

Sweating  small  perforations  in  the  surface  of  the  work  makes 

Process.  it  often  necessary  to  resort  to  some  means  of  filling 

them  in.    This  is  best  accomplished  usually  by  what 

is  known  as  the  sweating  process,  which  simply  implies  bridging  them 

over  with  solder. 


35 

This  may  apply  to  cases  requiring  investment  or  not,  and  the  pro- 
cedure in  either  instance  indicated  is  to  first  thoroughly  clean  the  parts 
and  then  fit  or  burnish  into  the  opening  a  piece  of  pure  gold  plate  or  foil 
of  suitable  dimensions,  which  may  be  held  in  place  by  holding  the  work 
in  a  favorable  position  to  sustain  it,  or  attaching  it  by  the  fusion  of  the 
flux.  A  piece  of  solder  somewhat  larger  than  the  perforation  should  then 
be  placed  in  position,  covering  same,  and  likewise  held  in  place,  and  then 
heat  uniformly  applied  until  the  solder  becomes  firmly  attached  without 
complete  fusion.  In  small  perforations  solder  alone  will  accomplish  this 
end,  without  the  use  of  a  support  of  pure  gold  or  other  metal. 

Autogenous  soldering  is  the  process  of  uniting 
HUtOgcnOUS  Soldering,  surfaces  by  immediate  inter-fusion,  without  the  use 
of  a  lower  grade  alloy  and  while  i>;  has  no  decided 
advantages,  excepting  that  a  joint  so  made  is  not  increased  in  stiffness  or 
thickness,  and  the  appearance  of  a  seam  of  solder  is  avoided,  it  is  quite 
easily  accomplished  in  uniting  bands  and  attaching  solid  cusps  to  them,  in 
the  execution  of  which  the  surfaces  must  be  perfectly  approximated,  re- 
tained closely  in  contact,  properly  fluxed,  and  held  in  the  flame  until  union 
is  accomplished  by  superficial  fusion.  By  a  little  practice  one  may  become 
quite  skilful,  and  joints  so  made  usually  possess  every  element  of 
strength. 

While  soft  soldering  is  not  to  be  generally  com- 

Soft  Soldering.  mended,    it    is    sometimes    indicated    in    emergency 

cases,  where  some  strength  in  the  union  of  the  parts 
is  required,  as  in  temporary  crowns,  etc.  For  such  purposes  a  solder 
composed  of  equal  parts  of  tin  and  lead,  or  any  of  the  fusible  alloys,  may 
be  used,  either  with  a  soldering  iron  or  by  placing  them  upon  an  asbestos 
pad  and  directing  the  flame  of  the  burner  upon  them  until  the  solder 
fuses.  A  convenient  flux  for  this  work  is  made  by  gradually  adding 
pure  zinc  to  hydrochloric  acid  until  the  chemical  action  subsides  or  the 
acid  refuses  to  take  up  more,  thus  making  a  solution  of  zinc  chloride, 
when  it  may  be  filtered  and  is  ready  for  use. 


^ 


Invcstittd  ana  Investment  materials. 


CHAPTER  IV. 

Object  of  Investing.     Requirements  of  Material.     Materials  Used.  Physical  Prop- 
erties.     Models.      Requirements    of    an    Investment.      Preparing    Case    for 
Investment.    Hard  Wax.    Adhesive  Wax.    Investing.    Small  Cases. 
Extensive  Cases.     Precautions.     Removing  Wax.     Prepa- 
ration of  Investment.     Drying  and  Heating.     Pre- 
pared   Compounds. 


One  of  the  most  important  features  to  be  observed  in  connection 
with  the  process  of  soldering  is  the  proper  investment  of  the  case,  the 
object  of  which  is  to  sustain  the  relation  of  the  parts  and  preserve  a  uni- 
formity of  temperature  during  and  succeeding  the  application  of  heat. 

By  investing  the  parts  the  uneven  or  too  rapid 

Object  heating  or  cooling  of  porcelain  facings  and  the  con- 

Of  TtlUCStinfl.  sequent   attending   dangers   are    obviated,   and   any 

possible  change  in  the  individual  relation  of  the  parts 

while  being  united  or  assembled  is  entirely  overcome. 

A  suitable  compound  for  such  purposes  should 

KC()Uircmcnt$  possess  the  essential  properties  of  crystallization,  in- 

Of  material.  fusibility,  free  conductivity  and  strength,  and  should 

neither  shrink  nor  expand  appreciably  during  the 

heating  process. 

Alany  substances  may  be  used  in  combination 
materials  Used.        with  plaster  of  paris,  which  is  necessarily  the  basis 
because  of  imparting  the  property  of  crystallization, 
and  which  must  be  incorporated  to  the  extent  of  at  least  50  per  cent. 

The  remaining  ])roportion  may  be  then  composed  of  such  materials 
as  will,  by  virtue  of  their  characteristics  and  physical  properties,  meet  such 
requirements.    The  following  are  serviceable  : 

Powdered  Silex,  Pulverized  Pipe  Clay, 

Fine    Asbestos,  Powdered  Fire  Brick, 

Beach  Sand,  Magnesium  Oxide, 

Marble  Dust,  I'umice  Stone, 


Z1 

A  combination  of  any  of  these  ingredients  in  van'ing  proportions 
with  the  proper  quantity  of  plaster  will  usually  possess  the  necessary 
qualities,  excepting  pumice  stone,  which,  because  of  its  low  fusibility  and 
inherent  tendency  to  expand  should  never  be  used,  and  asbestos  in  large 
proportions,  which,  while  serving  to  hold  the  mass  together,  when  mixed, 
is  objectionable  because  of  its  extreme  low  conductivity. 

The  property  of  free  conductivity  is  important 

Physical  Properties,      because  this  materially  lessens  the  time  consumed  in 

heating  the  case,  by  absorbing  and  distributing  the 

heat  more  rapidly   and  evenly,  and  by  thus   retaining  it  the  better  the 

soldering  is   facilitated,   and  the  liability  of   checking  porcelain   facings 

diminished. 

A  tendency  on  the  part  of  any  compound  to  expand  and  crack  open 
when  subjected  to  the  influence  of  heat  usually  indicates  that  the  texture 
is  too  fine  to  admit  of  the  rapid  evaporation  of  the  moisture,  and  as 
possible  displacement  of  the  parts  and  checking  of  facings  is  thereby 
promoted,  the  use  of  such  material  is  objectionable  and  unsafe. 

By  the  addition  of  a  coarser  ingredient  to  the  compound,  however, 
this  fault  may  be  overcome,  and  a  small  quantity  of  fine  shredded  asbestos 
will  also  frequently  eliminate  the  objection  in  a  measure,  without  greatly 
reducing  the  property  of  conducting  heat. 

While,  generally  speaking,  all  models  should  be 
models.  made  of  plaster  alone,  because  of  thus  possessing 

greater  strength,  smoother  surfaces  and  more  accu- 
rate and  definite  outlines,  while  ofifering  no  impediment  to  successful 
soldering  when  properly  prepared,  there  may  be  frequent  indications  for 
making  them  of  investment  material. 

In  such  instances  a  material  which  will  sjhrink  or  expand  appreciably 
is  decidedly  objectionable,  and  the  characteristics  of  that  used  for  such 
purposes  must  be  of  known  quantity,  for  the  reason  that  a  degree  of  in- 
accuracy in  the  relation  of  the  parts  and  their  proper  adaptation  may 
result. 

Where  such  a  model  seems  indicated  and  desirable,  and  especiallv  for 
the  purpose  of  the  final  assemblage  of  the  parts  in  extensive  cases,  a 
smooth,  well-defined  surface  may  be  secured  by  first  pouring  a  small 
quantity  of  thin,  well-mixed  plaster  into  the  impression,  then  inverting 
the  cup  until  all  surplus  runs  out.  leaving  only  a  thin  surface  coating, 
when  by  being  immediately  filled  with  the  investment  material,  a  model 
is  obtained  possessing  a  veneer  of  plaster. 


38 

As  the  object  of  investing  is  to  hold  the  parts  in 

Requirements  their  proper   relation  and  afitord  protection  to  the 

Ot  an  TnPestmCttt.       facings,  it  is  but  necessary  that  the  investment  should 

be  only  larg'e  enough  to  accomplish  this  end. 

Any  surplus  in  excess  of  merely  meeting  such  a  requirement  increases 


the   heat  necessary   and   adds   to   the   labor   involved   in  the   process   of 
soldering,  without  any  possible  advantage. 

In  assembling  the  individual  parts  on  the  model, 
Preparing  Case  for     some  means  should  be  observed  which  will  tempo- 
Tnuestment.  rarily  sustain  their  accurate  relation  until  they  are 

safely  transferred  to  the  investment.  In  this  partic- 
ular it  is  necessary  that  they  should  be  so  securely  united  as  to  prevent 
any  possible  displacement  during  the  process  of  removing  from  the  model, 
and  the  subsequent  imbedding  into  the  investment  material,  with  a  sub- 
stance sufficiently  tough  and  strong  to  withstand  such  procedure. 

This  is  usually  accomplished  by  using  a  hard  or  adhesive  wax  as  a 
medium  of  cementation,  which  in  large  cases  may  be  further  sup- 
plemented by  covering  the  facings  and  crowns  from  the  buccal  or  labial 
surfaces  with  a  thin  layer  of  j)laster  or  investment  compound  previous  to 
removing  from  the  articulator.     (Fig.  24.) 

In  interrupted  bridges  or  where  some  adaptation  of  bars  or  rests  to 
a  proper  relation  with  the  natural  teeth  is  indicated,  it  may  often  be  done 


39 

to  better  advantage  after  the  case  is  invested  than  when  on  the  model.  In 
such  instances  by  extending  or  continuing  the  wax  over  these  teeth  so  as 
to  secure  an  impression  of  them  before  detaching  and  investing,  their  ac- 
curate reproduction  may  be  secured  in  the  investment. 

For  the  purpose  of  thus  securely  cementing  the 
Uard  max.  parts  a  hard  wax  composed  of  from  two  to  four 

parts  of  resin  and  one  of  wax  is  reliable  and  much 
used.  The  combination  forms  a  stiff,  brittle  substance,  which  for  con- 
venience should  be  rolled  out  into  sticks  of  suitable  size  and  length.  These 
may  be  kept  indefinitely  by  coating  the  surfaces  with  whiting  or  plaster 
to  keep  them  from  adhering  to  each  other.  Parr's  fluxed  wax  may  also 
be  used  for  the  purpose. 

As  the  extreme  brittleness  of  hard  wax  is  some- 
Jldb($it>C  max.        times  objectionable,  a  less  brittle  and  more  adhesive 
compound  may  often  be  found  preferable.    The  fol- 
lowing   formula   gives   an   adhesive   wax   possessing   excellent   qualities : 
White  bee's  wax,  8  oz. ;  pulverized  white  resin,  13/2  oz. ;  gum  dammar, 
lyi  oz.     Alelt  in  order  named. 

When  the  various  parts  are  securely  and  firmly 
Investing.  united,  the  wax  should  then  be  carried  over  a  con- 

siderable surface  of  the  abutment  crowns  and  caps, 
including  every  portion  of  the  work  not  to  be  subsequently  covered  by 
investment  material.  This  procedure  serA^es  to  keep  such  surfaces  clean 
and  free  of  dirt,  and  leaves  them  fully  exposed  in  the  investment,  by  guid- 
ing the  flowing  of  same  over  only  those  parts  which  should  be  protected. 

In  all  cases,  ranging  from  a  single  crown  up  to 
Small  0a$C$.  four  or  five  teeth,  the  abutment  crowns  and  caps 

should  be  detached  from  the  model,  previous  to 
cementing  the  parts,  in  such  manner  as  to  preserve  their  definite  outline 
and  relation.  Upon  being  again  replaced  in  their  proper  position  all  of 
the  individual  parts  may  be  assembled  and  cemented  together,  when  the 
whole  can  be  easily  removed  and  invested.  This  eliminates  the  de- 
struction and  investing  of  the  model  and  preserves  it  for  future  use  in 
case  of  desire  or  necessity. 

In  larger  cases,  however,  it  is  not  usually  good 
€xtcn$it)C  Cases.        policy  to  follow  this  procedure,  because  of  the  in- 
creased liability  of  an  inaccurate  replacement  of  the 
abutment  caps  and  crowns,  especially  if  there  be  more  than  two.     In  such 
instances  it  is  always  safest  and  best  after  assembling  and  cementing  the 
parts  firmly  to  first  remove  the  model  from  the  articulator,  and  then  trim 


40 

away  all  surplus  plaster  until  only  enough  remains  to  sustain  the  relation. 
(Fig.  25.)  This,  then,  precludes  the  possibility  of  any  disarrangement 
or  displacement  of  the  parts,  and  the  remaining  plaster  is  of  no  signifi- 
cance if  entirely  submerged  and  completely  covered  with  the  invest- 
ment material. 

The  investment  compound  should  be  mixed  of 

Precautions.  a  moderately  thin  and  plastic  consistency,  so  that 

when  the  proper  quantity  is  poured  upon  a  piece  of 

paper  it  will  offer  no  resistance  in  pressing  the  case  down  into  place, 

until  it  is  properly  submerged  and  sufficiently  covered.     If  too  stiff  there 

would  be  danger  of  a  change  in  the  relation  of  the  parts. 

To  make  sure  of  a  close  adaptation  of  the  material  to  the  facings 
and  other  parts,  and  to  hold  them  securely  when  invested,  all  surplus 
wax  and  dirt  should  be  carefully  removed  and  the  case  dipped  in  water 
just  previous  to  bringing  it  in  contact  with  the  investment  material. 


Ficj.25. 

The  interior  of  all  crowns  and  caps  unless  previously  well  filled  with 
plaster  should  then  be  first  thoroughly  packed  with  the  investment  ma- 
terial by  using  a  small  piece  of  wood  or  fine-pointed  spatula;  because  if 
not  perfectly  filled  the  presence  of  air  spaces,  into  which  the  heat  becomes 
concentrated  during  the  process  of  soldering,  will  materially  increase 
the  liability  of  burning  or  fusing  the  parts,  an  accident  which  for  this 
reason  not  infrequently  occurs. 

After   the   investment  has  become   thoroughly 

Kemowing  Ulax.        hardened  and  the  surplus  trimmed  away,  the  wax 

should  be  slightly  warmed  by  passing  over  the  flame 

and  removed  as  well  as  possible  with  a  small  knife-blade  or  other  pointed 

instrument,  being  careful  not  to  loosen  or  dislodge  the  parts  in  so  doing. 

Hot  water  may  be  then  poured  upon  it,  but  the  case  should  never 
be  boiled,  for  the  reason  that  such  procedure  disintegrates  the  com- 
pound, interferes  with  its  perfect  crystallization,  and  requires  more  time 
in  drying  out  and  heating  U])  than  would  otherwise  be  necessary. 

Chloroform,  being  a  solvent  of  wax,  is  also  used  to  remove  remain- 
ino-  particles  but  this  is  entirely  unnecessary,  because  the  wax  will  be  ab- 
sorbed by  the  investment  and  ultimately  burned  out  entirely  during  the 
heating  process. 


41 

As   soon  as  the  wax  has  been  sufficiently  re- 
Preparatlon  moved,   the    investment    should   be   trimmed    down 

of  Investment.         until   no   larger   than    is    absolutely   required,   thus 
leaving  all  surfaces  upon  which  the  solder  is  to  be- 
come attached    freely  exposed,  so  as  to  ofifer  no  impediment  to  the  heat- 
ing of  the  case.     No  danger  will  accrue  from  this  free  exposure  of  the 


parts  if  the  porcelain  facings  are  covered  and  the  interior  of  crowns  and 
caps  well  filled,  and  the  labor  involved  in  the  process  of  soldering  will 
be  materially  lessened. 

The  investment  for  a  single  crown  should  be  cut  away  from  the 
approximal  sides  on  a  line  with  the  backing  and  cap.  (Fig.  26.)  Where 
this  is  not  observed  and  the  investment  remains  banked  up  on  these  sides, 


the  crown  is  imbedded  into  a  depression,  and  the  soldering  is  made  much 
more  difficult  because  the  flame  and  heat  from  the  blow-pipe  is  thus  de- 
flected from  the  parts. 

This  applies  as  well  to  more  extensive  work,  and  should  always  be 
closely  observed.  The  proper  exposure  of  the  metal  parts  and  the  neces- 
sary trimming  away  of  the  investment  for  larger  cases  is  illustrated  in 
Fig.  27. 

AMien  the  preparation  has  been  completed  and 
Drying  and  Seating,      all  particles  of  debris  removed,  the  parts  should  then 
be  fluxed,  and  the  case  placed  upon  the  burner  until 
it  gradually  becomes  sufficiently  heated  to  proceed  with  the  soldering. 


42 

Many  devices  are  provided  for  holding  the  case  in  the  flame,  but  the 
simplest,  most  useful  and  economical  method  is  to  put  it  upon  a  piece 
of  the  ordinary  metal  lathing  used  in  plastering,  which  is  made  of  iron 
and  is  more  or  less  durable,  and  then  place  this  upon  the  spider  over  the 
flame.      (Fig.  28.)  • 

Several    preparations    possessing   the    required 
Prepared  Compounds,    qualities  to  a  greater  or  less  extent  can  be  easily  pro- 
cured,  among  which   may  be   included   Dr.   R.   C. 


//iMi  V  ^  \    |\ 


nci28. 


Brophy's  "Imperial  Investment  Material,"  the  investment  compound 
made  by  the  Consolidated  Dental  INIanufacturing  Company;  "Sump," 
prepared  by  the  S.  S.  A^^hite  Dental  Manufacturing  Company,  and 
"Teague's  Compound,"  all  of  which  are  of  special  merit  and  can  be 
highly  recommended. 


Requirements  and 
Cecbnique  of  €rown  Construction. 


Tndications  and  Requirements. 


CHAPTER  V. 

Indications :  Extensive  Caries.     Accidental  Causes.     Discoloration.     Malformation. 

Malposition.    Requirements :  Physiological  Relations,  Anatomical  Relations. 

Stress.   Articulation  and  Occlusion.   Approximal  Contact.    IMechani- 

cal  Relations.    Method  of  Attachment.    Dowels.    Telescoping. 

Fit.     Strength.     Esthetic  Relations. 


Before  one  is  properly  prepared  to  consider  the  manipulative  proce- 
dure incident  to  the  detail  of  construction  of  artificial  crowns,  a  clear 
conception  and  a  thorough  understanding  of  the  indications  for,  and  re- 
quirements of  such  substitutes  for  the  natural  crowns  of  teeth  as  are 
generally  applicable  today  are  essentially  necessary. 

It  does  not  matter  particularl)-  in  what  line  of  art  or  mechanics  one 
confines  his  efforts,  to  meet  with  success  in  the  direction  chosen  requires, 
first  of  all,  the  necessity  of  formulating  in  the  mind,  or  picturing  in  the 
mental  eye,  the  result  of  the  contemplated  effort  in  the  finished  state, 
before  even  commencing  the  detail  of  its  construction. 

To  thus  conceive  the  possible  result  before  the  execution,  in  a  work 
where  art  and  mechanics  are  so  closely  related  to  nature,  greatly  enhances 
the  possibilities  by  cultivating  the  possession  of  those  lucid  and  perceptive 
ideas  which  are  so  essential  to  success  if  success  is  dependent  upon  the 
attainment  of  special  skill,  as  it  should  be. 

And  yet  while  dentistry  offers  no  greater  opportunities  for  the  ac- 
quirement and  display  of  the  highest  artistic  talent  than  in  the  field  of 
crown-work,  such  prerequisites  alone  will  not  always  insure  success,  but 
must  be  supplemented  by  a  degree  of  accuracy,  facility  and  delicacy  in 
instrumentation  which  will  at  once  inspire  the  confidence  of  the  patient. 

Thus  will  he  be  the  better  qualified  to  obtain  results  more  accurately 
restoring  the  normal  functions  and  more  closely  approaching  a  reproduc- 
tion of  nature ;  and  to  perform  them  for  the  most  nervous,  sensitive 
patients  with  more  gratifying  success  to  all  concerned. 


46 

In  this  field,  as  in  many  others,  those  methods  which  are  quickest 
and  test  are  not  necessarily  synonymous,  and  so  it  often  becomes  a  matter 
of  judgment  and  discrimination  as  to  the  employment  of  the  particular 
method  most  applicable  to  the  case  at  hand,  in  which  the  operator  must  be 
governed  only  by  the  most  scrupulous  and  conscientious  efforts. 

While  there  may  frequently  be  several  methods  of  procedure  that, 
at  the  first  conclusion,  seem  apparently  applicable,  there  is  usually  one  in 
particular  which  upon  closer  observation  will  best  meet  all  of  the  re- 
quirements. 

Tndications. 

The  employment  of  artificial  crowns  is  indicated  in  extensive  loss  of 
tooth  structure  from  the  ravages  of  caries,  or  accidental  causes,  and  not 
infrequently  because  of  discoloration,  malformation  and  malposition,  as 
a  means  of  substitution  for  the  correction  and  restoration  of  impaired 
function,  and  relief  from  disfigurement.  There  should  always  be  enough 
tooth  structure  ren'aining,  however,  to  insure  sufficient  anchorage. 

By  far  the  most  general  indication  is  in  those 
€xtcn$lcc  Caries.       instances  where  the  natural  tooth  structure  has  suf- 
fered such  irreparable  loss  from  the  process  of  caries 
as  to  make  restoration  by  filling,  with  any  assurance  of  permanency  in 
the  operation,  either  inadvisable  or  impossible. 

In  those  cases,  however,  where  it  seems  a  matter  of  conjecture  as  to 
the  advisability  of  filling  or  crowning,  unless  for  esthetic  reasons,  the 
preference  should  be  given  to  filling,  if  such  procedure  may  seem  to  offer 
any  certainty  of  a  reasonable  degree  of  success  and  permanency. 

In  frequent  instances  the  remaining  walls  of  badly  broken  down 
teeth  may  be  protected  and  usefulness  restored  for  many  years  by  the 
insertion  of  a  post  into  the  canal,  and  the  building  of  a  filling  around  it, 
and  such  a  course  is  often  indicated  for  the  reason  that  the  crowning 
operation  may  then  be  deferred  and  become  a  subsequent  and  possibly 
remote  necessity,  which  would  perhaps  add  to  the  aggregate  longevity 
of  the  root. 

Moreover,  the  presence  of  a  well-adapted  filling  is  no  doubt  more 
conducive  to  tbe  preservation  of  the  normal  condition  of  the  surrounding 
tissues,  than  the  most  skillfully  adapted  crown. 

The  loss  of  a  portion  or  all  of  the  natural  tooth 

Hccidcntal  Causes.      crown  in  the  anterior  region,  as  the  result  of  a  fall  or 

blow,  or  from  overstrained  masticatory  action  upon 

hard  substances  in  the  posterior  region,  is  by  no  means  uncommon,  and 

usually  calls  for  immediate  relief  in  their  reproduction  and  restoration. 


Discoloration. 


47 


The  presence  of  a  badly  discolored  tooth  in  the 
anterior  part  of  the  mouth,  which  persistently  re- 
fuses to  succumb  to  repeated  efforts  at  bleaching, 


Fi(j.29. 

may  often  indicate  an  artificial  substitute  as  the  only  means  of  effectually 
and  permanently  remedying  its  conspicuous  and  objectionable  appearance. 


Ficj.  30. 

In  such  conditions  of  faulty  enamel  formation 

malformation.  as  the  so-called  "peg"  laterals    (Fig.  29)    and  the 

pitted  enamel  structure,  as  is  frequently  found  to 

exist  in  the  first  permanent  molars  and  the  anterior  teeth  (Fig.  30),  the 


Fiq.SL 


application  of  an  artificial  crown  may  often  be  indicated  as  tlie  best  means 
of  restoring  usefulness  and  affording  relief  from  disfigurement. 

There  are  frequent  instances  of  simple  irregu- 

malposition.  larity  of  the  anterior  teeth,  where  the  age  of  the 

patient,  together  with  the  presence  of  caries  or  other 

conditions  may  not  seem  to  warrant  tlieir  correction  bv  the  process  of 


48 

regulating.  Often  the  desired  effect  may  be  obtained  by  sacrificing  the 
natural  crowns  and  substituting  artificial  ones  as  the  most  simple  and  artis- 
tic means  of  correcting  the  deformity.     (Fig.  31.) 

Rcquircittents. 

The  success  of  crown-work  in  the  various  phases  of  its  application, 
and  the  degree  of  permanence  in  the  operation,  combined  with  the  esthetic 
results  obtained,  depends  upon  a  close  observation  of  the  requirements 
from  a  physiological,  anatoniical,  mechanical  and  esthetic  standpoint. 

When  it  has  been  determined  that  a  crown  is 
Physiological  indicated  or  seems  to  be  the  most  advisable  proce- 

Kcl(ltion$.  dure,  it  is  first  necessary  to  ascertain  the  condition 

of  vitality  of  the  immediate  and  surrounding  tissues. 
If  pathological  conditions  exist,  every  effort  should  be  made  to  locate 
and  remove  the  cause,  and  the  usual  remedial  or  medicinal  agencies  should 
be  applied  until  the  tooth  or  root  assumes  as  healthy  and  normal  a  condi- 
tion as  possible  before  proceeding  further  with  the  operation. 

This  particularly  includes  the  thorough  disinfection  of  the  remaining 
tooth  structure,  and  the  removal  of  all  that  may  prove  irritating  to  the 
peridental  membrane.  The  precaution  is  necessary  because  the  presence 
of  an  artificial  crown  should  not  afford  any  more  reason  or  opportunity 
for  the  deleterious  action  of  disease-producing  agencies  than  when  the 
tooth  was  in  a  normal  healthy  condition ;  indeed,  it  should  even  further 
fortify  it  against  attack. 

In  regard  to  anatomical  relations  we  are  gov- 
Hnatomical  erned  by  the  position  of  the  root  and  the  artificial 

Relations.  crown  supported  by  it  in  their  relation  to  the  adja- 

cent and  antagonizing  teeth,  which  includes  the  con- 
sideration of  stress,  occlusion  and  approximal  contact. 

The  roots  of  teeth   carrying  crowns   are  sub- 
Strcss.  jected  to  the  influence  of  stress  in  different  direc- 

tions, according  to  their  location  in  the  arch,  which 
fact  demands  that  the  construction  and  application  of  artificial  crowns 
should  be  made  with  a  view  of  affording  a  degree  of  resistance  sufficient 
to  secure  the  greatest  integrity  of  both. 

As  the  line  of  the  greatest  natural  resistance  is  in  the  vertical  direc- 
tion, every  provision  should  be  made  tending  to  prevent  undue  and  un- 
natural stress,  which  might  ultimately  cause  displacement,  trouble,  or 
possible  loss  of  the  root. 

In  the  anterior  teeth  the  general  tendency  of  the  stress  imposed  is  to 
force  them  outward  and  forward,  which  may  and  should  always  be  re- 


49 

lieved  as  much  as  possible  by  the  proper  preparation  of  the  root,  the 
restoration  of  approxinial  contact,  and  the  method  employed  for  the 
attachment  of  the  crown. 

In  the  bicuspids  the  stress  is  received  in  both  vertical  and  lateral 
directions,  wdiich  demands  a  firm  seating  to  accommodate  the  former  and 
a  strong  method  of  anchorage  to  overcome  the  latter. 

The  molars  are  least  susceptible  to  displacement  for  the  reason  that 
lateral  stress  is  limited  in  proportion  to  the  degree  of  the  normal  accuracy 
of  occlusion ;  and  as  the  greatest  stress  is  in  the  direct  or  vertical  line, 
the  essential  requirement  is  a  good  firm  seating,  supplemented  by  accurate 
occlusion. 

The  degree  of  usefulness  and  longevity  of  the 

Jlrticulation  and        artificial  substitute  depends  greatly  upon  such  forma- 

Occlusion.  tion  of  the  articulating  surfaces,  and  in  the  posterior 

region  the  arrangement  of  cusps  and  sulci  in  their 

relation  to  the  antagonizing  teeth,  as  will  restore  their  normal  functions. 

The  arrangement  should  provide  for  correct  position  not  only  when  the 

teeth  are  in  direct  occlusion,  but  also  in  their  articulation  or  the  act  of 

bringing  them  into  occlusion. 

The  evils  of  faulty  and  imperfect  occlusion  are  often  apparent,  and 
result  frequently  in  marked  manifestations  of  virulent  peridental  and 
neurotic  troubles. 

The  restoration  of  approxinial  contact  is  of  the 
Jlpproximal  Contact,     greatest  importance,  and  is  made  so  because  of  the 
necessity  for  protecting  the  tissues  in  the  interproxi- 
mal spaces  from  the  serious  results  of  irritation. 

These  tissues  promptly  rebel  against  the  slightest  irritating  influences 
to  such  extent  as  to  demand  the  most  stringent  efforts  toward  their  pro- 
tection and  preservation. 

Due    thought    should    be    bestowed    upon    the 
IDccbankal  method  of  attachment,  fit  and  strength  of  artificial 

Relations.  crowns,  all  of  which  are  so  necessary  and  add  so 

materially  to  the  durability  and  degree  of  perma- 
nency in  the  work  from  a  mechanical  standpoint. 

Two  general  methods   of  attachment  are  em- 
lUctbOd  Of  Jittacblticnt.   ployed,  each  or  either  of  which  may  be  indicated  by 
the  style  of  crown  required,  and  the  amount  of  tooth 
structure  to  which  the  attachment  may  be  made. 

In  roots  which  are  even  with  or  approximating 

Dowels.  the   gingival    line,    attachment    must   necessarilv   be 

made  by  inserting  a  dowel  in  the  direction  of  their 


50 

longitudinal  axis  to  a  depth,  where  possible,  equal  to  the  length  of  the 
crown  from  cervix  to  incisal  or  occlusal  edge. 

Such  a  mechanical  fixation,  whether  the  dowel  be  previously  attached 
to  crown  or  root,  practically  precludes  the  loosening  of  the  parts  from 
strain,  at  the  line  of  junction,  overcoming  leverage  at  that  point  by 
distributing  it  throughout  the  length  of  root,  and  forms  a  most  secure 
means  of  anchorage. 

Where  enough  of  the  root  is  freely  exposed  to 

€ClC$C0Pin9.  afford  a  firm  grasp  of  the  crown,  the  attachment  may 

be    securely    made    by    telescoping,    in    which    the 

strength  at  the  line  of  junction  naturally  increases  in  proportion  to  the 

surface  of  tooth  structure  covered  by  the  crown. 

The  relation  existing  between  the  crown  and 

JfdaptatlOlt— Tit,        root  is  of  the  greatest  possible  importance,  because 

the  ratio  of  subsequent   failure  or  trouble  arising 

from  the  progress  of  caries,  or  from  gingival  or  peridental  irritation,  is 

decreased  in  proportion  to  the  degree  of  accuracy  in  the  adaptation. 

The  crown  should  be  seated  firmly  upon  the  root,  and  if  no  band  is 
used  the  adaptation  should  be  close  enough  to  make  a  joint  as  flush  and 
impervious  as  possible,  so  that  the  end  of  the  root  may  be  thus  pro- 
tected. 

When  a  band  is  used,  it  should  pass  under  or  within  the  free  margin 
of  the  gum  a  uniform  distance  on  all  surfaces  of  the  tooth  and  only  far 
enough  to  cover  and  protect  the  seam  of  union,  which  should  be  in  such 
close  proximity  to  the  root  as  to  preserve  its  continuity  and  make  a  smooth 
line  of  junction  between  the  two. 

The  durability  of  this  work  depends  to  a  very 
Strcitgtl).  large   extent  upon   its   inherent   strength,   which   it 

should  always  possess  to  a  degree  sufficient  to  per- 
manently withstand  the  stress  of  mastication,  even  though  it  be  gained 
at  the  sacrifice  of  more  or  less  artistic  results  when  occasion  requires. 
Any  tendency  toward  undue  economy  usually  proves  disastrous. 

These  considerations   embrace  the  field  which 

€$tI)CtiC  Relations.       gives  the  greatest  possible  scope  to  the  individuality 

and  artistic  temperament  of  the  operator,  and  while 

it  is  true  that  art  can  never  entirely  and  completely  take  the  place  of 

nature,  the  aphorism  is  less  applicable  to  this  special  line  of  work,  perhaps, 

than  to  any  other  department  of  dentistry  or  of  art. 

To  secure  the  highest  artistic  results,  the  artificial  crown  should  pre- 
serve the  gingival  outline,  and  the  symmetrical  alignment  of  the  teeth; 


51 

should  be  proportionate  in  length  with  the  adjacent  teeth,  and  if  of  porce- 
lain should  closely  match  them  in  color,  and  should  correspond  favorably 
in  general  form  and  characteristics  with  its  fellow  member  of  the  opposite 
side  of  the  arch. 

As  a  rule,  where  porcelain  is  used  no  metal  should  be  exposed  to 
view  from  any  surface,  unless  purposely  done  to  more  closely  match  the 
adjacent  teeth  or  the  corresponding  tooth. 

In  instances  where  the  remaining  natural  teeth  are  freely  filled  with 
gold,  the  artificial  substitute  should  often  carry  filling  which  will  enable 
it  to  more  closely  resemble  and  harmonize  with  them,  thus  making  detec- 
tion more  improbable,  which  legitimate  deception  is  a  true  evidence  of 
artistic  endeavor. 


tbc  Preparation  of  Roots. 


CHAPTER.  VI. 

Preliminary    Requirements :    Therapeutics.     Feasibility   of    Devitalization :    Physio- 
logical Considerations;  Mechanical  Considerations.     Treatment  of  Hypertrophy. 
Free  Exposure  of  the  Root.     Classification.     Preparation   for    Shell  or  Tele- 
scope   Crown:    Requirements;    Restoration    of    Continuity;    Diminution    of 
Coronal  Proportions;   Paralleling  Converging  or  Diverging  Teeth;  Opera- 
tive Procedure.     Preparation  for  Shell  or  Telescope  Crown  with  Porce- 
lain Facing:  Requirements.     Preparation  for  Band  and  Dowel  Crown; 
Requirements;    Operative    Procedure;    Excising    Incisors    and    Cus- 
pids; Excising  Bicuspids  and  Molars;   Removal  of   Enamel:  Use 
of  Enamel  Cleavers;  Peripheral  Trimming;  Shaping  Basal  Sur- 
face.    Preparation  for  Dowel  Crown  without  Band ;  Require- 
ments;   Operative    Procedure;    Inseparable    Dowels;    Separ- 
able Dowels;  Protection  of  Unsupported  Walls.     Prepara- 
tion   of    Canals;    Requirements;    Operative    Procedure. 
Treatment  of  Perforated  Roots.     Treatment  of  Frac- 
tured    Roots;     Posterior     Teeth;     Anterior     Teeth, 
Prognosis. 


Paramount  among  the  obstacles  in  the  pathway  of  success,  perma- 
nency and  comfort  in  crown  and  bridgework  is  the  perfunctory,  unskilful 
and  profoundly  indifferent  methods  so  often  employed  in  the  procedure 
incident  to  the  treatment  and  preparation  of  roots 

In  the  entire  subject  there  is  probably  no  one  distinctive  feature  of 
such  intrinsic  importance  as  the  practical,  scientific  and  skilful  prepara- 
tion of  the  remaining  crowns  and  roots  of  teeth,  for  the  reception  of  arti- 
ficial crowns. 

While  the  proper  and  necessary  operative  procedure  may  be  arduous, 
and  replete  with  attending  difficulties,  the  physiological  and  mechanical 
requirements  are  equally  exacting,  and  demand  the  same  degree  of  care, 
precision  and  accuracy  that  would  be  essential  to  the  preparation  of  the 
foundation  for  any  superstructure  designed  as  a  permanent  evidence  of 
skill  and  usefulness. 

More  particularly  is  this  true  in  our  efforts,  because  the  field  of  labor 
is  confined  to  living  sensitive  tissues  which  are  so  responsive  to  unnatural 
conditions  that  any  apparent  negligence  must  sooner  or  later  manifest 
itself,  not  alone  in  evidences  of  failure,  but  also  in  the  serious  discomfit- 
ures accompanying  the  various  stages  of  irritation. 


53 

These  usually  present  in  the  nature  of  gingival  inflammation,  and 
peridental  and  alveolar  absorption,  to  which  conditions  may  be  attributed  a 
very  large  percentage  of  the  troubles  arising,  and  the  absolute  loss  of  many 
teeth.  The  common  and  exciting  cause  of  such  prevalent  and  some- 
times discouraging  results  can  invariably  be  traced  to  faulty  and  imperfect 
adaptation  of  the  artificial  crown,  which  in  turn  reverts,  primarily,  to 
inadequate  and  unskilful  preparation  of  the  root  supporting  it. 

As  clinical  experience  proves  most  conclusively  that  comfort  and 
permanency  depend  upon  a  conservation  or  reproduction  of  the  natural 
conditions,  such  liabilities  decrease  of  course  in  proportion  to  the  degree 
of  accuracy  observed  in  the  operative  procedure. 

And  as  a  degree  of  accuracy  may  only  be  obtained  by  an  appreciaT 
tion  of  the  significance  and  importance  of  the  requirements,  a  broad  com- 
prehension of  the  underlying  mechanical  principles,  and  a  thorough,  con- 
scientious execution  of  the  details  is  necessary. 

To  facilitate  this  the  consideration  of  the  subject  must  necessarily  be 
in  accordance  with  a  more  or  less  scientific  and  systematic  arrangement, 
in  the  order  of  the  practical  application  of  the  principles  and  technique 
involved. 

Preliminary  KcquiremcntSo 

When  it  has  been  determined  that  an  artificial  crown  is  indicated  the 
first  essential  features  to  be  observed  should  always  include  a  considera- 
tion of  those  requirements  constituting  the  preliminary  operative  proce- 
dure incident  to  placing  the  roots  in  the  most  favorable  condition  possible 
for  the  subsequent  permanent  attachment  of  the  crown. 

The  very  first  detail  is  obviously  that  of  the 
CbCrapcutiCS.  therapeutic    treatment    necessary    in    securing    an 

as'eptic  condition  of  the  root,  including  pulp  canals 
and  surrounding  tissues. 

This  should  invariably  precede  the  removal  or  destruction  of  any  of 
the  remaining  walls,  because  of  the  facility  which  their  retention  affords 
for  the  application  of  the  rubber  dam,  which  is  essentially  desirable  and 
advantageous  in  rendering  tiie  field  immune  from  secretions  while  med- 
icinal applications  are  being  made. 

After  the  removal  of  all  disintegrated  structure,  the  usual  remedial 
agencies  indicated  by  the  requirements  and  the  existing  conditions  should 
be  consecutively  applied,  until  tJwroiigh  asepsis  of  sufficient  potency  to 
preclude  any  possibility  of  subsequent  disease  or  disintegration  is  obtained. 

When  this  has  been  successfully  accomplished,  the  pulp  canals 
should  be  thoroughly  filled  throughout  their  entire  length,   irrespective 


54 

of  the  style  of  crown  indicated,  and  the  root  fiUing  then  temporarily  cov- 
ered and  protected  with  cement  to  exclude  the  deteriorating  influences 
of  moisture  during  its  hardening  and  crystallization. 

TedsiDility  of  Devitalization. 

The  problem  of  the  feasibility  of  sacrificing  the  vitality  of  pulps  in 
teeth  which  are  to  be  subsequently  crowned  is  one  of  great  importance, 
and  is  a  portion  of  the  operative  procedure  incident  to  the  preparation  of 
such  teeth,  which  requires  the  most  conscientious  and  conservative  con- 
sideration. 

For  many  years  no  special  thought  was  given  to  this  feature,  and 
such  teeth  as  seemed  to  indicate  restoration  by  crowning  were  treated 
much  in  the  same  manner  as  though  fillings  were  to  be  inserted. 

The  frequency  of  subsequent  troublesome  manifestations,  however, 
including  the  ultimate  death  of  pulps  with  the  attending  consequences 
of  such  pathological  conditions  as  virulent  peridental  inflammations  and 
alveolar  abscesses,  have  since  caused  the  subject  to  be  more  carefully  con- 
sidered, until  it  is  now  most  generally  conceded  to  be  a  safer  precaution, 
in  a  great  majority  of  cases,  to  destroy  such  pulps  as  a  prophylactic  proce- 
dure as  well  as  to  facilitate  the  necessary  mechanical  preparation,  when 
the  crown  is  to  entirely  cover  the  end  of  the  root. 

It  is  now  a  more  or  less  generally  acknowledged 
PbysiOlOgical  belief  of  the  most  eminent  authorities  that  the  pulp 

Considerations.  is  purely  a  formative  organ,  and  that  its  physiological 
function  terminates  with  complete  development  of  the  tooth;  that  it  is 
not  necessary  to  its  vitality,  stability  and  longevity  after  maturity,  pro- 
viding that  the  pulp  cavity  is  perfectly  filled;  thus  there  seems  to  be  no 
good  reason  for  its  preservation,  taking  into  account  the  modern  aseptic 
means  of  removing  it  and  treating  and  filling  the  canals. 

Especially  is  this  true  where  a  crown  is  indicated,  because  the  abnor- 
mal encasing  of  the  tooth  so  as  to  practically  isolate  it  must  at  least  dimin- 
ish the  external  influences  of  secretions  and  temperature  upon  the  nerve 
and  blood  su])ply  of  the  pulp ;  and  because  usually  such  teeth  have  already 
been  subjected  to  the  irritating  and  devastating  influences  of  caries,  each 
of  which  seems  but  to  invite  and  pave  the  way  for  ultimate  destructive 
processes. 

Other  deleterious  influences  may  come  from  the  irritating  action  of 
the  cements  used  in  mounting,  or  from  the  efl^ects  of  the  shock,  or  over- 
stimulation induced  1)y  the  necessary  mechanical  preparation,  either  of 
which  may  often  prove  important  factors  in  rendering  such  teeth  sus- 
ceptible to  a  "slow  but  often  complete  and  unnoticed  destruction." 


55 

All  things  considered,  the  prophylactic  measure  seems  the  conserv- 
ative one,  and  as  modern  scientific  root  treatment  offers  no  palpable  ex- 
cuse for  subsequent  pathological  conditions,  it  seems  that  the  orthodox 
dogma  of  preservation  is  inapplicable  to  a  great  majority  of  cases, 
where  experience  and  judgment  teach  us  the  demand  for  a  perhaps  more 
"radical"  but  manifestly  safer  procedure. 

The  contraindication  for  such  treatment  would  be  in  the  mouths  of 
patients  under  sixteen  years  of  age,  where  in  all  probability  complete  devel- 
opment of  the  tooth  had  not  yet  been  attained.  In'such  instances,  however, 
it  would  be  as  unwise  to  pass  the  crown  entirely  beneath  the  gum  as  it 
would  be  to  destroy  the  vitality  of  the  pulp,  unless  both  were  necessary. 
And  after  fifty  years  of  age  the  necessity  for  such  treatment  is  often 
greatly  diminished  because  of  the  physiological  phenomena  of  the  gradual 
atrophy  of  the  pulp,  and  the  formation  of  secondary  dentine,  which  :>o 
lessens  the  sensitiveness  of  the. structure  as  to  admit  freely  of  the  neces- 
sary preparation,  while  reducing  the  probability  of  the  ultimate  occur- 
rence of  pathological  conditions  to  a  minimum. 

Occasional  exceptions  may  also  be  warranted  in  those  cases  of  ab- 
normal development,  faulty  enamel  formation,  extensive  abrasion  as  a 
result  of  attrition,  and  where  the  absence  of  adjacent  and  occluding  teeth 
makes  necessary  but  little,  if  any,  preparation,  but  such  indications  can 
only  be  governed  by  experience  and  judgment. 

Because  these  considerations  apply  more  par- 
niecbanical  ticularly  to  the  posterior  teeth,  where  the  shell  or 

Considerations.  telescope  crown  is  indicated,  and  where  the  removal 
of  a  considerable  portion  of  the  remaining  tooth 
structure  becomes  an  absolute  requirement,  the  destruction  of  the  pulp  is 
usually  imperative  as  a  means  of  making  possible  and  facilitating  the 
necessary  preparation  in  the  diminution  of  the  coronal  proportions  of  the 
natural  crown. 

When  the  vitality  is  preserved,  this  procedure,  alwavs  exacting,  is 
ordinarily  so  difficult  that  it  must  be  either  perfunctorily  and  negligently 
performed,  or  else  the  patient  must  be  made  to  tolerate  an  exceedingly 
and  often  excruciatingly  painful  operation. 

Frequent  evidences  of  flagrant  indift'erence  and  negligence  are  so 
manifest  as  to  prove  conclusively  that  in  a  large  majority  of  cases  the  vig- 
orous eft'orts  necessary  to  secure  the  best  and  most  successful  results  may 
only  be  obtained  under  the  most  favorable  conditions. 

Crcattticnt  of  l^ypertropby. 

In  instances  where  an  exuberant  growth  or  hypertrophy  of  pulp  or 
gum  tissue  is  present,  or  may  have  almost  entirely  covered  the  end  of  the 


56 

root,  some  difficulty  may  be  experienced  in  applying  the  dam  and  pur- 
suing the  necessary  course  of  treatment. 

Both  may  be  greatly  facilitated,  however,  by  the  immediate  excision 
and  removal  of  such  tissue  at  the  first  sitting,  and  if  the  continuity  of  the 
root  be  destroyed  by  disintegration,  or  if  its  length  will  not  admit  of  the 
application  of  the  clamp  and  rubber  dam,  a  temporary  restoration  can  be 
easily  effected  by  adjusting  a  band  of  German  silver  closely  encircling 
the  circumference  of  the  root,  as  soon  as  the  suppression  of  the  hemor- 
rhage, by  the  use  of  styptics,  will  permit. 

Such  a  band,  if  properly  and  carefully  fitted  to  the  neck  of  the  root, 
and  trimmed  so  as  to  have  no  sharp  or  irregular  edges,  and  not  to  inter- 
fere with  the  occlusion,  will  at  once  admit  of  the  application  of  the  dam 
by  adjusting  the  clamp  over  it,  and  may  remain  in  place  and  be  worn  with 
comfort  until  the  necessary  treatment  and  final  filling  of  the  canals  has 
been  accomplished. 

If  filled  flush  to  the  edge  with  temporary  stopping  at  the  end  of  each 
treatment,  it  further  serves  to  hermetically  seal  the  dressing  within  the 
root,  and  to  compress  the  tissues  so  as  to  afford  a  free  exposure  of  the 
periphery. 

Trw  exposure  of  fbe  Root. 

During  the  process  of  treatment  in  all  badly  broken  down  roots  some 
means  should  always  be  employed  to  compress  the  tissues  in  such  manner 
as  to  freely  expose  the  end,  which  greatly  facilitates  the  fitting  of  the 
band,  or  the  adjustment  of  the  crown,  and  materially  lessens  the  usual 
discomfiture  attending  the  operation. 

When  the  use  of  a  temporary  band  is  not  indicated,  or  seems  unneces- 
sary, the  same  advantages  may  be  gained  by  packing  temporary  stopping 
into  and  over  the  end  of  the  root,  and  under  the  free  margin  of  the  gum. 

Tf  the  root  is  too  shallow  to  anchor  it  securely,  it  may  be  so  retained 
by  packing  tightly  against  the  adjacent  teeth,  or  held  firmly  by  ligatures 
attached  to  them,  or  by  inserting  a  small  sharp  tack  through  it  and  into 
the  tooth  structure. 

In  instances  where  the  accumulation  of  gases  demand  some  vent,  a 
perforation  may  be  made  through  the  stopping  at  a  convenient  [)oint. 

Care  should  also  be  exercised  to  prevent  undue  pressure,  which,  if 
existing  for  an  indefinite  time,  might  possibly  cause  injury  to  peridental 
membrane  or  surrounding  tissues,  as  a  result  of  protracted  lack  of  cir- 
culation. 


57 


Classification. 

The  principles  involved  in  the  necessary  preparation  of  roots  are 
governed,  of  course,  by  the  particular  style  of  crown  indicated,  and,  while 
crown  work  is  divided  into  two  general  classes,  according  to  the  method 
of  attachment  employed,  a  variation  in  the  essential  details  of  their  indi- 
vidual construction  requires  that  each  class  be  subdivided,  and  that  the 
subject  be  considered  in  four  general  classes. 

In  order  to  meet  the  requirements  occasioned  by  this  variation,  each 
class  will  be  considered  separately,  and  are  as  follows : 


Preparation  for  shell  or  tele- 
scope crown. 

Preparation  for  shell  or  tele- 
scope crown  with  porcelain  facing. 


Preparation  for  band  and  dowel 
crown. 

Preparation  for  dowel  crown 
without  band. 


Preparation  for  $bcn  or  telescope  Crown. 

The  detail  of  procedure  indicated  by  the  require- 
KC()Uit*Cm(nt$.  ments  for  a  shell  or  telescope  crown,  because  of  be- 

ing generally  confined  to  the  posterior  teeth,  is 
usually  the  most  difficult,  and  should  be  closely  observed. 

In  those  instances  where  the  ravages  of  exten- 
Kcstoration  of         si\e  decay  have  caused  the  destruction  of  the  remain- 
£ontinuity.  i^g  walls  of  the  natural  crown,  so  as  to  carry  the 

cervical  border  at  some  point  wdthin  or  beyond  the 
free  margin  of  the  gum,  some  means  of  permanent  restoration  of  the  con- 
tinuity of  the  root  is  usually  advisable. 

This  prevents  the  possible  fracturing  of  unsupported  walls  during 
their  preparation;  adds  materially  to  the  integrity  of  the  root;  greatly 
facilitates  the  fitting  of  the  band,  and  overcomes  the  probability  of  sub- 
sequent disintegration  arising  from  an  imperfect  adaptation  of  the  band 
to  the  margins  of  deep  cervical  pockets. 

Such  restoration  can  usually  be  best  accomplished  with  amalgam,  the 
use  of  which  affords  a  better  opportunity  for  securing  a  close  adaptation 
between  it  and  the  margins  of  the  root,  with  the  assurances  of  a  greater 
degree  of  permanency. 

Where  the  edge  of  the  band,  however,  can  be  fitted  closely  to  the 
root  at  all  points  around  its  entire  circumference,  with  a  reasonable  de- 
gree of  certainty,  and  where  the  walls  are  weak,  the  use  of  cement  for 
this  purpose  is  preferable,  because  of  the  additional  support  rendered  by 
its  adhesive  qualities,  and  because  any  further  destruction  of  the  tooth 


58 

structure  for  the  purpose  of  securing  retention  is  unnecessary;  but  when 
the  extreme  depth  of  the  marginal  edge  (Fig.  32)  makes  a  close  adapta- 
tion of  the  band  either  impossible  or  doubtful,  amalgam  should  be  used. 

In  using  amalgam  adequate  retention  must  be  secured  in  the  pulp 
chamber,  or  root  canals  if  necessary.  A  thin  circular  matrix  of  German 
silver,  g.  34-36,  should  then  be  adapted,  and  so  shaped  as  to  make  the 
restoration  of  suitable  form  to  save  further  preparation.  After  adjusting 
this,  its  inner  surface  should  be  coated  with  vaseline,  oil,  or  any  lubricat- 


ing substance,  to  prevent  adherence  of  the  amalgam,  and  insure  its  easy 
removal  after  crystallization.  To  admit  of  and  facilitate  this  the  amal- 
gam should  never  extend  as  high  as  the  edge  of  the  band,  and  a  subsequent 
sitting  is  usually  necessary.     (Fig.  33.) 

In  roots  where  the  entire  crown  has  been  destroyed,  it  is  usually 
necessary  to  rebuild  and  restore  a  portion  of  it,  in  order  to  better  and 
more  securely  sustain  the  artificial  crown,  by  obtaining  greater  integrity 
between  it  and  the  root  at  the  line  of  junction.     This  may  be  easily  ac- 


r/a.33. 


complished  by  adjusting  the  matrix,  and  firmly  inserting  a  screw-post 
into  the  most  accessible  canal,  additionally  fortified  with  cement  (Fig. 
34  j,  and  then  building  up  with  amalgam  to  the  desired  length  and  shape. 

The  diminution  of  the  natural  crown,  or  its  re- 
Diminution  of  maining  walls,  in  a  manner  favorable  to  the  require- 

COi'onal  Proportions,     ments,  is  frequently  a  very  difficult  procedure  be- 
cause of  the  usual  inequality,  in  teeth  of  normal  pro- 
portions, between  the  diameters  of  the  crown  and  the  cervix. 


59 

This  requires  and  necessitates  the  removal  of  considerable  tooth 
structure  in  order  that  the  circumference  may  be  reduced  at  every  point 
occlusally,  and  at  the  uniform  expense  of  each  surface,  at  I'east  equal  to 
the  exact  dimensions  at  the  cervix. 

While  it  is,  of  course,  desirable  to  leave  as  much  as  possible  of  the 
remaining  coronal  portions,  it  will  be  observed  from  the  illustrations 
(Fig.  35)  that  approximately  about  one-sixteenth  of  the  structure  from 
the  axial  walls,  and  the  occlusal  one-fourth  must  be  removed. 


Such  a  requirement  is  not  a  hypothesis,  but  a  physical  and  mechan- 
ical problem  which  must  necessarily  be  closely  observed,  in  order  that  it 
may  be  made  possible  for  the  band  to  approximate  a  close  adaptation  to 
the  normally  constricted  neck;  and  to  admit  of  a  reproduction  of  the 
occlusal  service  in  the  artificial  crown  possessing  sufficient  thickness  to 
withstand  the  influences  of  constant  attrition. 

To  further  increase  the  opportunities  for  securing  a  closer  continuity 
between  crown  and  root,  the  remaining  walls  should  not  merely  be  parallel, 


f/a,3S. 


but  should  be  slightly  inveried,  so  that  the  band  may  fit  more  closely  as  it 
is  pressed  root7i'ise,  and  thus  prevent  its  edge  from  being  forced  i)ito  the 
gum  tissue,  instead  of  under  or  zi'itliiu  the  free  margin. 

This  requirement  is  indisputably  essential  when  the  crown  is  intended 
to  approach  or  pass  beneath  the  gum,  if  comfort  and  permanency  are  to 


6o 

be  obtained  from  the  operation,  and  is  one  of  the  strongest  arguments  in 
favor  of  the  devitalization  of  the  pulp. 

Owing  to  the  general  tendency  of  teeth  to  gravi- 

Paralleling,  tate  or  tip  tov^ard  the  unoccupied  area  in  interrupted 

Converging  or  arches  (Fig.  36),  in  their  preparation  for  bridgework 

Diverging  Ccetb.        it  is  essential  to  observe  that  the  surfaces  of  each 

individual  root  presenting  toward  each  other,   are 

made  absolutely  perpendicular,  as  illustrated  in  Fig.  37. 

Such  a  condition  wdll  frequently  be  found,  and  no  matter  how  per- 


Fitj.ae, 


fectly  each  individual  root  should  be  prepared,  the  presentation  of  per- 
pendicular lines  is  necessary  to  admit  of  the  adjustment  of  the  bridge 
after  completion. 

Operative  Procedure. 

As  this  portion  of  the  operation  is  particularly  trying  to  the  patient, 
as  well  as  the  operator,  a  good  assortment  of  stones,  disks  and  burs,  kept 
sharp,  even-edged,  and  mounted  true,  is  essential,  and  all  unnecessary 
grinding  should  invariably  be  avoided. 

When  any  of  the  walls  of  the  tooth  remain  or  approximate  their  full 
length,  the  first  detail  should  be  to  undermine  the  enamel  to  the  desired 
point  by  cutting  away  the  dentine  with  a  sharp  bur.  Such  walls  may 
then  be  easily  broken  down  with  the  excising  forceps,  and  much  unneces- 
sary grinding  thus   avoided.     The   surface   of   the  occlusal   end    should 


6i 

be  ground  smooth  with  a  thick-edge  stone.  The  buccal  and  lingual  walls 
may  be  reduced  with  a  thin-edge  stone  of  suitable  diameter,  in  which 
it  is  essentially  necessary  to  keep  the  revolving  stone  moving  upward  and 
downward  against  the  surface  of  the  tooth,  to  prevent  the  formation  of  a 
shoulder  or  ridge  at  any  point,  and  to  assure  a  uniform  reduction. 

After  these  walls  have  been  adequately  reduced,  the  trimming  of  the 
approximal  walls,  usually  the  most  difficult,  is  next  in  order.    When  they 


F/j.3  8. 

remain  high  enough  to  afford  considerable  support  to  the  enamel,  grind- 
ing must  still  be  resorted  to,  as  the  cleavers  will  be  found  practically  use- 
less in  detaching  and  removing  it  unless  it  is  more  or  less  disintegrated. 

For  such  purposes  a  thin-edge  stone  or  diamond  disk  of  suitable 
diameter  may  be  used,  by  beginning  from  the  occlusal  end,  at  a  point 
about  one-sixteenth  of  an  inch  from  the  periphery,  and  cutting  through 
on  a  slight  angle  until  the  interproximal  space  is  reached. 


F/p.Ss9, 


A  small  cross-cut  fissure  bur  inserted  into  the  interproximal  space  at 
right  angles  to  the  teeth,  and  brought  ocdusally  with  considerable  pres- 
sure against  the  root,  may  often  serve  as  a  valuable  supplement  to  the 
stone,  or  sometimes  answer  the  purpose  itself,  if  sufficient  care  be  exer- 
cised to. prevent  mutilating  the  adjacent  teeth,  which  may  often  be  pro- 
tected with  a  band  matrix. 

When  adjacent  teeth  are  absent,  the  procedure  is  less  difficult  and 
may  be   accomplished   with   a   blunt   safe-edge   stone,   as   illustrated   in 


62 

Fig.  38,  or  a  stone  possessing  the  shape  of  an  inverted  cone.  The  latter  is 
very  often  found  most  useful  in  reducing  the  surfaces  of  molars. 

If  the  remaining  walls  are  short,  and  the  enamel  is  somewhat  disin- 
tegrated, the  cleavers  may  be  found  very  useful. 

When  sufficient  diminution  of  the  structure  has  been  secured,  the 
sharp  corners  should  be  nicely  rounded  with  burs  and  sandpaper  disks, 
and  the  necessary  preparation  is  then  completed. 

The  degree  of  accuracy  thus  obtained  will  be  denoted  by  the  freedom 
and  facility  with  which  the  measurement  wire  may  be  detached  from  the 
root  after  being  twisted  taut,  and  the  buccal  and  occlusal  aspects  should 
present,  as  indicated  in  Fig.  39. 


Da  ^4, 


:■"■"■''■;  if'  i 
1  / 


^■7.  4  0. 
Preparations  Tor  Sbcll  or  telescope  Crown  wltb  Porcelain  facing. 

While  the  same  general  principles  apply  to  the 
Requirements.  necessary  preparation  for  a  shell  or  telescope  crown 

with  porcelain  facing,  and  the  same  detail  of  proce- 
dure is  indicated,  a  variation  is  required. 

This  variation  comprises  grinding  down  the  buccal  wall  sufficiently 
to  accomodate  the  presence  of  the  facing,  as  the  area  to  be  occupied  by 
it  must,  of  course,  be  gained  at  the  expense  of  the  remaining  root,  (Fig. 
40.) 

This  should  never  be  done,  however,  until  after  all  other  require- 
ments, as  before  outlined,  have  been  observed,  and  it  may  be  done  to  even 
better  advantage  after  the  band  has  been  fitted. 


Preparation  for  Band  and  Dowel  Crown, 

The   requirements  of   root  preparation    for   a 

Ke<)Ulretncnt$.  band   and    dowel    crown   are   similar   in   peripheral 

features  to  the  requirements  for  a  shell  or  telescope 


63 

crown,  but  differ  in  that   all  of  the   remaining  natural   crown  must,  of 
course,  be  sacrificed  to  more  nearly  approximate  the  gum  line. 

This  is  necessary  because  the  line  of  junction  between  crown  and 
root  is  made  at  this  point  in  order  to  accomodate  the  artistic  and 
esthetic  presence  of  a  porcelain  facing. 

Operative  Procedure. 

In  the  operative  procedure  incident  to  removing  the  remaining  por- 
tions of  the  natural  crown,  as  much  of  it  as  possible  should  be  cut  away 
and  broken  down  to  a  certain  point,  in  order  to  avoid  all  unnecessary 
grinding. 


In  the  incisors  and  cuspids  this  may  be  quickly 

Excising  Incisors       and   easily   accomplished  by   first   undermining  the 

and  Cuspids.  remaining   enamel    with    a    bur,    and    then    cutting 

grooves  through  it  at  a  point  which,  when  the  crown 

is  excised,  will  leave  a  projecting  end  of  the  root  about  one-sixteenth  of 

an  inch  beyond  the  gum  line.     (Fig.  41.) 

Care  should  be  exercised  in  cutting  the  grooves  entirely  through  the 
enamel,  so  as  to  relieve  or  reduce  the  shock,  and  prevent  a  fracture  root- 
wise.  The  beaks  of  the  excising  forceps  may  then  be  placed  in  the 
grooves,  and  the  crown  easily  and  safely  removed. 

In    removing    the    remaining    portion    of    the 
Excising  Bicuspids      crown  of  bicuspids  and  molars,  the  grooves  and  ex- 
and  Itlolars.  cising  forceps  possess  the  same  advantages. 

In  their  use,  however,  any  remaining  continuity 
between  buccal  and  lingual  walls  must  also  be  first  attacked  with  a  bur  to 
destroy  their  integrity.  (Fig.  42.)  This,  in  conjunction  with  grooves, 
will  facilitate  their  excision  without  shock  or  danger  of  fracture. 


64 

The  remaining  ledge  of  enamel  upon  this  pro- 

Kemoval  of  €namcK      jecting  end  of  the  root,  which  has  been  purposely 

retained,  for  the  time,  must  then  be  removed  in  order 

to  bring  the  greatest  diameter  beneath  the  gum,  where  the  line  of  junction 

between  band  and  root  is  to  be  made.     This  can  be  best  accomplished  by 

the  use  of  enamel  cleavers  designed  for  the  purpose. 

The  use  of  enamel  cleavers  of  any  design  may 
Use  Of  enamel         or  may  not  be  of  a  desired  degree  of  effectiveness ; 
Cleaners.  according  to  the  manner  in  which  they  are  manipu- 

lated,   and   the    easy    and    expeditious    removal    of 
enamel  depends  entirely  upon  their  proper  manipulation. 

The  edge  of  the  cutting  blade  of  the  instrument  must  be  placed  above 
the  enamel  and  held  at  the  prop-er  angle  in  its  relation  to  the  surface  of 


/7^ 


.43. 


F/g.^^-, 


the  root ;  and  a  fulcrum  must  be  established  to  facilitate  the  application 
and  exertion  of  the  necessary  force  to  secure  the  destruction  of  what  is 
usually  a  very  dense  attachment. 

The  adjacent  tectli,  when  present,  will  serve  as  a  means  of  estab- 
lishing such  a  fulcrum ;  and  in  their  absence  the  same  may  often  be  se- 
cured by  placing  a  smooth  piece  of  soft  wood  or  rubber,  of  sufficient 
thickness,  against  the  incisal  or  occlusal  ends  of  remaining  teeth,  or  the 
gums,  against  which  the  thumb  may  rest  as  a  means  of  affording  oppor- 
tunity for  securing  purchase  and  leverage. 

While  various  styles  of  instruments  have  been  suggested  for  this 
purpose,  those  designed  by  Dr.  C.  S.  Case  (Fig.  43)  will  be  found  adimr- 
ably  adapted  to  upper  anterior  roots;  and  those  designed  by  Dr.  A.  G. 


65 

Johnson  (Fig.  44)  are  especially  useful  for  posterior  and  lower  roots, 
though  adapted  for  universal  use.  The  manner  of  holding  them  in  the 
hand  and  securing  purchase  upon  adjacent  teeth  is  illustrated  in  Fig.  45. 

After  all  enamel  has  been  removed,  the  pe- 
Pcripbcral  Criltimlng*  riphery  of  the  root  should  be  made  smooth  and  to 
present  a  perpendicular  line,  as  indicated  before  ana 
after  in  Fig.  46.  This  can  be  easily  accomplished  with  a  small  fissure 
bur;  or,  a  set  of  trimmers  suggested  by  Dr.  J.  H.  Prothero  (Fig.  47),  or 
the  "Root  Reducer,"  manufactured  by  the  S.  S.  White  Co.  (Fig.  46)^ 
both  of  which  are  designed  for  this  purpose,  and  may  be  found  useful. 


F/q,  45.  Ficj.ai.    Ficj.Q-t 

Before  considering  the  final  shaping  of  the  end 
Shaping  Basal  or  basal  surface  of  such  roots,  it  may  be  well  to  em- 

Surface.  phasize  that  they  have  been  purposely  left  projecting 

somewhat  beyond  the  gum,  as  indicated,  until  the 
peripheral  preparation  is  complete,  because  of  thus  materially  facilitating 
the  removal  of  enamel,  and  the  subsequent  taking  of  the  measurement  and 
fitting  of  the  band,  and  for  the  reason  that  this  freely  exposed  and  project- 
ing surplus  end  serves  to  retain  the  wire  until  an  accurate  measurement 
may  be  secured,  and  to  conform  the  band  to  the  proper  shape  and  guide  ii 
to  place  in  fitting. 

The  fitting  of  the  band  is  thus  made  practically  free  from  discom- 
fiture to  the  patient,  and  easy  for  the  operator,  and  after  it  has  been  fitted 
and  trimmed  to  the  desired  width,  the  root  should  then  be  cut  down  to 
the  proper  form  of  base. 

The  shape  given  the  basal  surface  of  the  root  is  of  much  importance, 
and  particularly  in  the  upper  anterior  teeth,  where  the  requirements  make 
it  desirable  to  leave  the  lingual  edge  somewhat  longer  than  the  labial  in 


66 


order  to  afford  greater  mechanical  resistance  to  the  stress  naturally  im- 
posed,, and  to  carry  the  labial  edge  a  trifle  beneath  the  gum,  so  that  the 
band  or  cap  may  be  invisible,  and  the  neck  of  the  porcelain  facing  placed 
in  close  proximity  to  the  gum  line. 

Compliance  with  these  mechanical  and  esthetic  requirements  results, 
of  course,  in  beveling  the  end  of  the  root,  as  indicated  in  Fig.  49  (which 

111--/   \ 


Fic^.^-9.  Fia.50. 


Ficj.5/, 


is  the  common  practice),  or  in  shaping  it  on  a  slight  and  gradual  inclined 
plane,  as  illustrated  in  Fig.  50.  The  latter  is  the  best  and  preferable 
preparation,  because  of  affording  greater  opportunities  for  the  adapta- 
tion of  the  cap  and  facing  without  causing  undue  prominence  at  the  neck 
(a  common  fault  with  artificial  crowns),  and  with  a  minimum  of  grinding 
of  the  facing,  and  a  maximum  of  strength  in  the  crown. 


Ficj.5P. 


Fiq.53. 


This  can  be  best  accomplished  with  a  flat-edge  carborundum  or 
"vulcan"  carborundum  stone  (Fig.  51),  kept  wet  when  using  (the  latter 
having  the  advantage  of  wearing  true),  until  the  gum  line  is  reached, 
when  the  (Jttolengui  root-facers  (Fig.  52)  are  most  useful  in  cutting  it 
beneath  the  gum  on  the  labial  or  buccal  edges,  without  lacerating  the 
tissues.    These  should  be  of  the  "safe-sided"  variety,  and  are  made  in 


67 

three  sizes,  to  accommodate  the  size  of  root  and  the  space  between  adja- 
cent teeth,  and  should  be  used  with  extreme  care,  as  they  cut  rapidly. 

In  the  preparation  of  bicuspid  and  molar  roots,  where  the  stress  is 
direct,  it  is  usually  desirable  to  leave  the  basal  surface  almost  Hat,  as  in- 
dicated in  Fig.  53.  This  allows  more  opportunity  for  securing  strength 
in  the  finished  crown,  and  adds  to  the  possibilities  for  its  closer  adapta- 
tion and  for  an  observance  of  the  more  artistic  and  esthetic  requirements. 

In  no  instance,  however,  should  this  final  preparation  be  made 
until  the  band  has  been  fitted. 

Preparation  for  Dowel  Crown  without  Band. 

In  the  preparation  of  roots  for  the  dowel  crown  zvithout  band,  the 
same  procedure  applies  to  the  removal  of  the  remaining  natural  crown, 
as  indicated  in  the  preparation  for  this  style  of  crown  with  a  band. 

After  the  remaining    portions    of    the    natural 
KeOUircmcntS.         crown  have  been  sacrificed,  however,  the  essential 
features  differ  somewhat  in  the  shape  given  to  the 
basal  surface,  and  in  that  the  removal  of  enamel,  or  any  peripheral  prep- 
aration, is,  of  course,  entirely  unnecessary. 

Operative  Pr^cednre. 

As  the  permanency  and  success  of  such  crowns  depend,  to  a  great 
extent,  upon  the  degree  of  accuracy  secured  in  the  adaptation  to  the  root, 
its  end  must  be  so  shaped  as  to  render  the  opportunities  for  a  close  adapta- 
tion most  favorable. 

In  the  preparation  for  that  style  of  crown  in 

Tnscparable  Dowels,     which  the  dowel  is  an  integral  part  (as  the  Logan 

crown),  the  form  given  to  the  basal  surface  should 

be  exactly  as  indicated  before,  in  Fig.  50,  and  the  procedure  is  identical, 

excepting  the  removal  of  enamel. 

This  preparation  becomes  necessary  because  the  presence  of  an  im- 
movable dowel  makes  the  grinding  of  the  crown  to  adaptation  with  the 
root  somewhat  difficult  at  best,  but  which  is  facilitated,  of  course,  by  hav- 
ing the  root  present  as  smooth  a  surface  as  possible.  The  labia!  surface 
may  then  be  brought  in  contact  with  the  gum  margin,  which  is  desirable 
for  esthetic  reasons,  while  the  line  of  junction  upon  the  lingual  surface 
will  be  in  accord  with  prophylactic  measures  in  being  rendered  self- 
cleansing  by  exposure  to  the  secretions  and  movements  of  the  tongue. 


The  difficulty  in  adapting  such  crowns  because 
Scp^rabU  Dowels,      of  the  interference  of  the  dowel  in  grinding,  consti- 
tutes the  advantages  possessed  and  afforded  by  those 
wdth  separate  dowels,  such  as  the  Davis  crown. 

Where  it  is  intended  to  construct  the  crown  with 
PlaU  and  DOWel«       plate  and  dowel  as  separate  parts,  to  be  subsequently 
attached  with  solder,  and  where  the  close  adaptation 
of  the  plate  may  be  secured  by  swaging  or  burnishing,  the  lingual  por- 
tion should  also  be  beveled  almost  to  the  gum  line.     (Fig.  54.) 

By  thus  saddling  the  end  of  the  root,  greater  mechanical  resistance 


is  offered  to  the  displacement  of  the  crown,  while  the  prophylactic  require- 
ments are  secured  in  a  better  adaptation  of  the  surface,  and  a  closer  ap- 
proximation of  the  edge  of  the  plate  to  the  periphery  of  the  root. 

In  roots  which  present  a  concave  base  as  the  re- 

ProtCCtlon  of  suit   of  extensive  decay,  the  walls   should    first  be 

Unsupported  UlallS.     ground  down  until  smooth,  and  as  dense  as  the  mar- 
ginal outlines  noted  will  admit,  and  then  supported 
with  a  suitable  material. 

W'lien  the  continuity  remains  unbroken,  cement  will  best  answer  the 
purpose,  but  if  some  restoration  seems  necessary,  the  use  of  amalgam  is 
usually  indicated  for  the  reasons  mentioned. 

As  mechanical  retention  is  frequently  impossible,  in  these  roots, 
some  difficulty  may  be  experienced  in  anchoring  it  where  its  use  is  indi- 
cated, but  this  may  be  accomplished  by  first  thoroughly  roughening  or 
serrating  the  dentine  with  a  wheel-bur,  and  then  flowing  over  it  a  thin 
coating  of  cement  and  immediately  packing  the  amalgam  to  place. 

The  cement  thus  aids  materially  in  securely  anchoring  the  amalgam, 
and  a  more  permanent  restoration  is  often  afforded. 

In  very  extensive  decay  these  walls  may  sometimes  be  better  sup- 


69 

portH  by  forming  the  base  of  the  crown  itself  to  closely  fit  them,  so  as  lo 
offer  the  necessary  protection  when  mounted  with  cement. 

Preparation  of  Canals. 

The  preparation  of  the  canal  for  the  reception  of  the  dowel  should 
always  be  the  last  procedure,  and  is  of  special  significance  since  the  dowel 
plays  such  an  important  part  in  the  retention  and  stability  of  this  style  of 
crown. 

The  necessary  preparation  consists  in  enlarging 

KedUirettKntS.         them  sufficiently  to  receive  a  dowel  proportionate  in 
sise  zmth  the  diaineter  and  probable  length  of  the 
root,  and  consistent  with  the  requirements  of  the  crozvn.      Any  further 
enlargement  and  destruction  of  tooth  structure  is  injudicious  and  unneces- 
sary. 

One  dowel  is  sufficient  to  support  any  crown,  providing  that  it  may 
extend  into  the  root  a  depth  equal  to  the  length  of  the  crown  (Fig,  55), 


Ficj.  55. 

which  is  a  mechanical  requirement,  and  possess  strength  enough  to  with- 
stand the  stress. 

In  upper  first  bicuspid  and  in  molar  roots,  however,  if  the  probable 
length  or  constriction  of  the  root  precludes  this,  two  may  be  used. 

After  first  so  determining  the  size  of  dowel  indi- 

Operatioe  Procedure,    cated.  or  to  be  used,  in  the  individual  case,  the  canal 

should  then  be  enlarged  to  receive  it.     A  twist  drill 

or  sharp  round  bur  approximating  the  same  diameter  as  the  dowel  should 

then  be  selected,  and  the  canal  reamed  out  to  adequate  proportions. 

In  most  instances  it  is  desirable  to  extend  the  opening  into  the  canal 
somewhat  lingually,  in  order  to  permit  the  dowel  to  pass  through  the 
cao  at  a  point  which  will  carry  its  projecting  and  surplus  end  out  of  the 
wa-*^,  so  as  not  to  interfere  with  the  adjustment  of  the  neck  of  the  facing 
to  proper  relation. 

Considerable  care   should   be  exercised,   especially  in   bicuspid   and 


70 

constricted  roots,  to  avoid  drilling  through  the  sides  of  the  root,  as  such 
perforations  usually  cause  much  trouble,  and  may  often  result  in  the  loss 
of  the  root. 

For  this  reason  the  round  bur  is  considered  the  best  and  safest  means 
of  enlarging  canals,  because  if  of  a  proper  size,  and  carefully  guarded, 
as  it  approaches  the  periphery  an  immediate  response  will  be  manifested 
from  its  approaching  proximity  to  the  peridental  membrane,  in  ample 
time  to  cause  cessation  of  drilling  and  prevent  perforation  of  root. 


treatment  of  Perforated  Roots. 

The  presentation  of  perforations  through  the  root,  whether  from 
accidental  causes  or  as  the  result  of  caries,  is  usually  a  most  aggravating 
state  of  affairs,  and  calls  for  much  painstaking  effort  to  again  place  such 
a  root  in  condition  to  remain  permanently  comfortable. 

A  hermetical  and  non-irritating  seal  is  required,  for  which  purpose 
soft  gold  foil,  tin  foil,  cement,  white  paraffin  and  gutta  percha  are 
generally  used. 

While  all  possess  some  good  qualities,  the  use  of  chemically  pure  tin 
foil  is  most  universally  successful. 

When  these  cases  present,  all  septic  and  inflamed  conditions  of  im- 
mediate and  surrounding  tissues  should  first  be  relieved  by  the  proper 
medicinal  applications.  A  small  cone  of  chemically  pure  tin  foil,  about 
No.  4  thickness,  should  then  be  rolled,  and  inserted  into  canal,  until  one 
end  is  passed  through  the  perforation.  With  a  smooth,  blunt,  root  canal 
plugger,  the  remaining  portion  of  the  cone  should  be  gently  packed 
against  the  walls  over  and  surrounding  the  perforation,  and  then  small 
pellets  of  slightly  moistened  cotton  should  be  packed  into  the  canal  to 
burnish  the  tin  to  close  adaptation. 

Upon  the  removal  of  the  cotton  the  tin  may  be  protected  and  held  in 
place  by  covering  witli  cliloro-percha  and  filling  the  root  with  cement. 

When  such  treatment  becomes  necessary  before  filling  the  canals, 
their  location  may  l^e  preserved  to  admit  of  same  by  the  insertion  of  a 
broach  into  each,  the  subsequent  removal  of  which  will  leave  them  still 
accessible  for  further  treatment  and  final  filling,  through  tlic  open- 
ings thus  made. 

The  use  of  tin  is  preferable  to  other  materials,  because  it  is  easily 
adapted,  even  in  the  presence  of  moisture,  and  is  absolutely  non-irritating, 
and  offers  a  still  greater  advantage  in  the  hermetical  sealing  afforded  by 
the  subsequent  formation  of  the  oxide,  which  chemical  action  is  induced 
by  contact  with  the  moisture  of  the  tissues. 


71 

treatment  of  Tractured  Roots. 

The  not  infrequent  presentation  of  fractured  roots,  and  the  difficul- 
ties usually  encountered  in  their  treatment,  require  a  definite  knowledge 
of  the  various  means  employed  to  restore  and  preserve  their  usefulness, 
and  a  delicacy  and  dexterity  of  manipulation  in  the  procedure. 

In   the  posterior  teeth  these  conditions  usually 
Posterior  Cectb,        result  from  overstrained  or  undue  masticatory  force 
upon  such  teeth  as  may  have  been  weakened  by  the 
presence  of  extensive  decay,  or  very  large  fillings,  involving  the  approx- 
imal  and  occlusal  surfaces,  and  causing  a  longitudinal  fracture  of  the  re- 
maining crown  and  root. 

Such  fractures  usually  extend  from  mesial  to  distal  surfaces,  separat- 
ing the  buccal  from  the  lingual  cusps,  and  may  often  be  successfully 
treated  and  permanent  usefulness  restored  by  crowning  the  root. 

When  such  a  course  seems  indicated,  the  first  procedure  should  be  the 


Ficj.  56. 

thorough  removal  of  all  loose  particles,  by  freely  washing  and  flooding  the 
tooth  with  tepid  water,  until  a  perfect  and  close  approximation  of  the 
parts  may  be  secured. 

This  approximation  should  then  be  securely  retained,  temporarily, 
until  permanent  fixation  may  be  obtained  by  mechanical  means. 
This  may  be  accomplished  by  using  well  annealed  German  silver,  or  or- 
dinary silver  suture  wire,  from  23  to  26  g.,  which  should  be  passed  around 
the  circumference  of  the  tooth  at  the  neck,  and  the  ends  then  twisted 
tightly  together. 

The  German  silver  wire  is  preferable  because  of  admitting  of  greater 
strain  without  breaking,  and  if  therapeutic  treatment  is  necessary  it 
may  then  proceed  until  the  tooth  and  adjacent  tissues  are  placed  in  favor- 
able condition. 

The  mechanical  procedure  then  necessary  to  firmly  and  permanently 
anchor  the  parts  is  governed  by  the  extent  of  structure  possessed  by  each 
independent  portion. 


72 

If  enough  remains  of  each  portion,  they  may  be  securely  attached  by 
cutting  dovetail  grooves  in  each,  and  then  flowing  a  thin  layer  of  cement 
over  the  entire  interior  surface,  thus  utilizing  its  adhesive  properties,  and 
then  filling  with  amalgam.     (Fig.  56.) 

When  the  latter  has  become  thoroughly  craystallized,  the  wire  may 
be  removed,  and  the  tooth  carefully  shaped  for  the  reception  of  the  crown. 
When  insufficient  structure  in  one  of  the  parts  precludes  this  procedure, 
the  desired  result  may  be  accomplished  by  first  wiring  securely,  and  then 
adjusting  the  rubber  dam  and  completely  filling  the  tooth  with  thin 
cement. 

If  the  presence  of  moisture  is  prevented,  the  adhesive  properties  of 
the  cement,  in  conjunction  with  the  wire  around  the  neck,  will  usually 
retain  the  parts  until  the  tooth  has  been  shaped,  if  care  be  exercised.  In 
this  particular,  the  stone  should  ahvays  revolve  toward  the  fracture  in 
order  to  prevent  displacement. 


FiQ.  51. 


The  wire  may  then  be  removed,  and  the  crown  fitted  and  mounted. 

Such  fractures  in  the  anterior  teeth  usually  oc- 

Jlnterior  Ccctb.        cur  as  the  result  of  a  blow  or  other  accident ;  or  from 

the  stress  of  mastication  upon  an    artificial    crown 

offering  no  protection  against  such  strain  and  perhaps  mounted  upon  a 

root  already  weakened  by  too  extensive  or  injudicious  enlarging  of  the 

canal  for  the  reception  of  the  dowel. 

When  the  fracture  does  not  extend  beyond  the  border  of  the  alveolus 
to  any  appreciable  extent,  it  is  usually  best  to  remove  the  loose  portion, 
compress  the  tissues  with  gutta  percha,  and  restore  with  amalgam.  Or 
if  the  necessary  retention  is  not  possible,  the  base  of  the  crown  may  be 
closely  adapted  to  the  root,  and  the  restoration  made  with  the  crown. 

When  the  fracture  extends  beyond  the  alveolus,  however,  it  is  usually 
desirable  to  secure  fixation  and  retain  the  loosened  portion,  in  order  to 
prevent  the  resorption  following  its  loss. 

This  may  be  accomplished  by  cementing  and  wiring  until  sufficient 
preparation  can  be  made  to  admit  of  the  adjustment  of  the  crown. 


73  - 

If  each  portion  possesses  sufificient  structure,  additional  strength  may 
often  be  secured  in  their  fixation  by  the  use  of  an  uiiradciital  band. 

Where  the  length  and  thickness  of  the  fractured  part  may  seem  to 
indicate  such  a  procedure,  the  parts  should  first  be  tightly  wired,  as  sug- 
gested, and  then  a  circular  groove  trephined  a  consistent  depth  through 
the  thickest  part  of  each,  into  which  a  band  may  be  subsequently  fitted 
(Fig.  57),  by  the  use  of  a  very  simple  outfit  suggested  by  Dr.  B.  J. 
Cigrand.  When  the  band  has  been  adjusted  to  the  groove  and  ground 
smooth  with  the  basal  surface  of  the  root,  a  firm  secure  fixation  of  the 
parts  is  insured,  and  the  wire  may  then  be  removed  and  the  crown  ad- 
justed. 

While  some  little  suppuration  and  trouble  may 
PrOflttOSlS.  be  subsequently  present  as  a  result  of  reuniting  frac- 

tured roots,  it  should  give  no  unnecessary  appre- 
hension because  if  properly  treated,  and  absolute  immobility  has  been 
secured,  it  is  usually  of  but  temporary  nature,  and  many  roots  so  treated 
seem  permanently  restored  to  usefulness,  indicating  a  very  favorable 
prognosis. 


Cbe  Shell  or  telescope  grovptt. 


CHAPTER   VII. 

Indications,  Contraindications,  Requirements :  Telescoping  Portion,  Occlusal 
End,  Methods:  Sectional  Method,  Procedure;  Measurement,  Bands;  Width, 
Length,  Soldering,  Fitting,  Contouring,  Occluding  Bite,  Impression.  Articulators. 
Processes  for  Cusp  Formation,  Carved  Cusp  and  Special  Die  Methods.  Procedure ; 
Swaged  Cusps,  Mould,  Dies,  Swaging,  Adjusting  Cusps,  Soldering  Cusp,  Finishing. 
Solid  Cast  Cusps.  Cusp  Formation  without  Models.  Use  of  Ash's  Crown  Swaging 
Device.  Die  and  Die-Plate  Methods;  Individual  Dies,  Die-Plates;  Application,  Ad- 
justing With  Models.  Adjusting  Without  Models.  HoUingsworth  System ;  Appli- 
cation. Millett's  System,  Application.  Lowry  System;  Application.  Baird  System; 
Application.  Seamless  Method:  Advantages.  Disadvantages;  Time,  Strength, 
Adaptation.  Detail  of  Construction;  Primary  Band,  Bite  and  Impression,  Prepar- 
ing Model,  Casting  Flasks,  Dies,  Forming  Blanks,  Swaging,  Adapting  and  Re-en- 
forcing. Reverse  Process:  Advantages,  Disadvantages,  Procedure;  Original 
Model,  Mould,  Swaging-Model,  Blanks,  Swaging,  Methods,  Scott's  Method,  Finish- 
ing. Application  to  Separated  Molar  Roots ;  Procedure,  Bands,  Cusps.  Applica- 
tion to  Individual  Roots.  Cantilever  Bridges.  Application  of  Amalgam:  With 
Band,  Without  Band.  Application  to  the  Anterior  Teeth:  Indications,  Procedure; 
Adaptation  to  the  Mouth.  Adaptation  to  Models.  Carving  and  Swaging.  Die- 
plate  Methods;  Lowry  and  Millett  Systems;  HoUingsworth  and  Baird  Systems. 
Seamless  Method :  Reproductions.  Dowels.  Ready-made  Forms.  Removing  and 
Repairing;  Crown  Slitting  Forceps.     Preserving   Continuity  of   Bands.      Repairing. 


Brief  reference  has  already  been  made  to  the  history  and  usefulness 
of  the  gold  shell  or  telescope  crown,  and  to  this  style  of  crown  as  having 
been  one  of  the  early  achievements  in  the  preservation  of  badly  decayed 
teeth   or  roots,  and  the   restoration   to   their   former  functional   activity. 

Regardless  of  the  progress  and  development  of  crown  work  in  gen- 
eral, however,  and  irrespective  of  the  esthetic  and  hygienic  advantages 
of  porcelain  work,  this  style  of  crown  is  still,  and  probably  always  will  be, 
one  of  the  very  best  means  and  methods  of  subserving  the  requirements. 
Indeed,  when  their  application  is  indicated,  and  when  the  adaptation  and 
construction,  by  whatever  method  chosen,  is  practically  and  skilfully 
executed,  no  other  one  method  of  procedure  seems  to  offer  so  great  an 
opportunity  for  the  serviceable  and  permanent  reproduction  of  the 
normal  condition. 


75 

As  a  natural  consequence,  and  because  of  the  time-proven  value  of  a 
method  affording  such  opportunities  and  possessing  the  possible  quali- 
ties of  strength  and  indestructibility  to  so  great  an  extent,  many  roots  have 
been  permanently  saved  and  made  useful  that  would  otherwise  have  been 
lost ;  bridge-work,  both  faxed  and  removable  in  character,  has  deve'.- 
oped  and  become  practical ;  and  yet  the  esthetic  and  artistic  possibilities  of 
modern  prosthesis  have  been  most  flagrantly  abused  by  injudicious  use, 
and  indiscriminate  application. 

If  dentistry  is  to  become  universally  acknowledged  as  a  profession 
embracing  a  field  of  dignified  and  scientific  pursuit,  and  if  dental  pros- 
thesis is  ever  to  be  accorded  the  recognition  and  distinction  of  an  art,  to 
which  the  scope  of  its  possibilities  entitle  it,  the  somewhat  common  prac- 
tice of  placing  gold  crowns  on  teeth,  within  the  range  of  vision  in  the 
mouth,  violating  all  traditions  of  art,  must  be  considered  as  degrading, 
and  should  be  most  vigorously  condemned. 

No  matter  how  skilfully  the  operation  may  be  made,  or  how  perfect 
the  result  obtained,  such  evidences  of  artificial  handiwork  whenever  prom- 
inently conspicuous  are  an  offense  to  art,  culture  and  refinement. 

As  a  result  of  the  appreciation  by  the  laity  of  more  artistic  endeavor, 
and  their  education  at  the  hands  of  those  conscientious  enough  to  exercise 
their  duty,  the  request  for  such  work  is  now  so  limited,  and  so  few  will 
even  tolerate  them,  that  the  pernicious  practice  is  of  necessity  confined 
mostly  to  either  unscrupulous  charlatans,  or  to  those  who  wilfully  cater  to 
a  perverted  taste  and  a  barbaric  vanity. 

As  many  teeth  requiring  artificial  crowns,  how- 

Tndications.  ever,  are  beyond  the  range    of   vision,    gold    crowns 

may  often  be  used  without  objection,  and  to  the  best 
possible  advantage. 

Their  application  is  indicated,  principally  in  restoring  the  roots  of 
molars,  and  occasionally  of  second  bicuspids,  but  rarely  anterior  to  them. 

In  cases  of  close  occlusion,  where  the  cusps  of  the  opposing  teeth 
when  brought  into  direct  occlusion  afford  but  little,  if  any  opportunity  for 
securing  sufificient  strength  with  any  style  of  porcelain  crown  ;  and  on 
roots  so  short,  disintegrated  and  weakened  as  to  require  support  and  resto- 
ration with  amalgam,  especially  in  the  mouths  of  men  where  their  pres- 
ence may  not  be  conspicuous  because  of  the  beard,  their  application  to  the 
a^'st  bicuspids  may  be  sometimes  permissible ;  also  in  the  preparation  of 
bicuspids  which  are  to  serve  as  abutments  for  bridgework,  where  it  seems 
advisable  to  allow  the  natural  crown  to  remain  as  long  as  possible,  in 
order  to  afford  greater  integrity  in  the  attachment  of  the  artificial  crown, 
and  thus  secure  increased  mechanical  resistance  to  the  stress  imposed 
upon  the  bridge. 


7^ 

Anterior  to  the  molars,  however,  and  particu- 
£ontraindication$.  larly  in  the  mouths  of  women,  their  application  is 
usually  contraindicated  in  view  of  the  more  artistic 
means  available.  Any  exceptions  should  be  based  only  upon  a  conscien- 
tious consideration  of  the  existing  conditions  and  practical  requirements 
of  the  case ;  and  their  application  to  the  incisors  and  cuspids,  in  any  event, 
should  be  regarded  as  an  unpardonable  offense. 

Kequiretncnts. 

The  requirements  for  this  style  of  crown  do  not  dift'er  essentially 
from  those  of  crown  work  in  general,  as  previously  outlined.  Whenever 
and  wherever  employed,  they  should  be  constructed  of  a  material  thick 
and  heavy  enough  to  possess  adequate  strength  ivhen  finished,  and  suffi- 
ciently high  in  karat  to  withstand  the  chemical  action  of  the  secretions. 

The  band  or  that  portion  which  telescopes  the 
telescoping  Portion,  end  of  the  root  should  fit  closely  around  the  entire 
circumference ;  pass  a  sliort,  but  uniform,  distance 
beneath  the  gingival  border  of  the  gum,  and  possess  a  smooth  rounding 
edge  so  as  to  offer  no  possible  irritating  influence  to  the  tissues  surround- 
ing it.  It  should  also  be  contoured  to  typical  form,  restore  the  points  of 
contact,  and  preserve  a  proportionate  and  symmetrical  alignment,  with 
the  adjacent  teeth. 

The    cusps    forming    the    occlusal    end    should 

Occlusal  end.         mimic  or  approach  a  typical  reproduction  of  the  indi- 
vidual tooth ;  restore  the  normal  occlusion  by  contact 
with  opposing  teeth  at  several  points,  and  offer  no  interference  to  the  lat- 
eral motion  of  the  jaw  in  the  various  movements  of  articulation. 

They  should  also  be  deep  and  sharp  enough  to  aid  in  the  act  of  mas- 
tication, and  of  sufficient  thickness  to  withstand  constant  and  continued 
attrition. 

A  very  common  fault  with  a  large  majority  of  these  crowns  is  the 
presentation  of  a  more  or  less  smooth  and  uninterrupted  masticating  sur- 
face. Such  a  condition  precludes  the  proper  mastication  of  food,  and 
minimizes  the  possibilities  of  service  and  usefulness,  which  may  be  easily 
obtained,  and  which  qualities  such  substitutes  for  the  natural  condition 
should  always  possess. 

The  general  usefulness  of  this  style  of  crown  has  resulted  in  the 
presentation  from  time  to  time  of  an  innumerable  variety  of  methods  and 
systems  for  their  construction. 

The  degree  of  skill  possessed  Ijy,  and  the  personal  preference  of  oper- 


17 

ators  enter  into  the  use  of  all  of  them  to  such  an  extent  as  to  have  so  far 
prevented  the  adoption  of  any  particular  one  as  a  universal  system. 

Two  general  methods  of  construction  are  employed — the  Sectional 
and  the  Seamless,  and  each  has  many  diversified  processes. 

The  sectional  method,  wherein  the  band  and 
Sectional  method,  cusp  are  made  separately  and  subsequently  united,  is 
the  most  commonly  used.  This  procedure  seems  to 
afford  more  absolute  accuracy  in  securing  adaptation ;  even  better  oppor- 
tunities for  the  reproduction  of  the  necessary  contour ;  consumes  less  time, 
and  admits  of  the  use  of  a  heavier  gauge  of  gold  throughout  the  construc- 
tion of  the  crown.  These  important  advantages  cause  it  to  be  readily 
accepted  as  the  most  universally  successful  method. 

The  joint  made  in  the  union  of  band  and  cusp  offers  no  objectionable 
features,  and  in  no  way  interferes  with  artistic  possibilities,  if  the  edges 


of  each  are  closely  and  perfectly  approximated,  and  the  union  made  with 
a  solder  closely  resembling  the  gold  in  color,  and  sufficiently  high  in  karat 
to  withstand  the  chemical  action  of  the  secretions  without  subsequent 
discoloration. 

In  the  procedure  incident  to  the  mechanical  con- 

Proccdure.  struction    of    a    crown    possessing    a    band    by    any 

method,  the  first  detail  is  obviously  that  of  securing  a 

true  measurement  of  the  diameter  of  the  root  to  serve  as  a  positive  guide 

in  obtaining  a  band  of  accurate  dimensions. 

For    this    purpose    wire,    thin,    narrow    copper 
measurement.         strips,   and  waxed   floss  are  used.      Bessemer  steel 
wire,  about  No.  32,  is  preferable,  however,  because  of 
being  easier  to  adjust  and  handle,  and  more  reliable. 


78 

It  should  be  cut  in  suitable  length,  made   in    circular    form,    some 
what  larger  than  the  root,  and  the  ends  then  securely  attached  in  a  small 
dentimeter,  avoiding  any  unnecessary  surplus. 

While  many  varieties  of  dentimeters  have  been  suggested,  a  small 
jeweler's  slide  pin-vise  affords  the  quickest,  easiest  and  most  secure  ad- 
justment, with  less  danger  of  cutting  the  wire  when  twisting. 

The  loop  of  wire  should  be  then  placed  over  the  root,  passed  just 
freely  beneath  the  gingival  border  of  the  gum,  and  twisted  taut,  being 
careful  in  the  meantime  to  conform  and  adapt  it  to  all  concavities  of  the 
root.     Fig.  58. 

In  very  short  roots,  it  may  become  necessary  to  hold  it  under  the 
gum  with  a  suitable  instrument,  to  prevent  displacement  while  twisting; 
and,  while  it  is  usually  most  convenient  to  have  the  twist  upon  the  buccal 


fjq.60. 


or  labial  surfaces,  in  second  and  third  molars  it  may  sometimes  be  found 
more  convenient  to  twist  from  the  lingual  surface. 

After  securing  the  correct  measurement  of  the  diameter  of  the  root 
the  wire  should  be  cut  in  two  at  a  point  farthest  away  from  the  twisted 
portions,  and  each  end  of  the  former  loop  then  carefully  straightened  out 
until  smooth,  continuous  with  one  another,  and  at  right  angles  with  the 
dentimeter.     Fig.  59. 

When  two  or  more  crowns  are  being  constructed  for  the  same  mouth 
'.It  the  same  time,  especially  when  the  roots  are  nearly  of  a  size,  each 
measurement  should  possess  some  characteristic  to  distinguish  it  from  the 
other,  by  which  means  any  confusion  in  the  subsequent  fitting  of  the 
band  may  be  avoided.  This  may  be  easily  accomplished  by  so  bending  or 
shaping  the  surplus  ends  as  to  differentiate  between  them,  and  have  each 
designate  the  root  which  it  represents. 


79 

As  the  strength  possessed  by  the  crown,  in  its 
Bands.  attachment  to  the  root,  increases  in  proportion  to  the 

thickness  of  the  gold  of  which  the  band  is  made,  so 
long  as  it  is  not  too  heavy  to  be  easily  manipulated  and  accurately  adapted, 
and  as  gold  stretches  easily,  and  its  thickness  is  necessarily  diminished  by 
the  subsequent  process  of  finishing  and  polishing,  28  gauge  (B.  &  S.) 
plate,  about  22  karat  in  fineness,  should  be  used  for  bands.  A  gold  for 
this  purpose  is  especially  prepared  by  the  Consolidated  Dental  Mfg.  Co. 
which  is  alloyed  slightly  with  platinum,  and  possesses  the  advantages  of 
strength  and  toughness  as  well  as  being  non-oxidizable,  by  which  name  it 
is  designated. 

The  desired  width  of  the  band  should  be  noted 
lUidtb.  with  the  eye,  or,  if  necessary,  measured  with  a  piece 

of  cardboard  trimmed  to  the  correct  width,  or  with  a 
small  compass.     Fig.  60. 

In  cutting  the  gold  the  cervical  edge,   or  that 

CdtStb.  which  is  to  be  fitted  to  the  root,  should  be  the  exact 

length  of  the  measurement  wire ;  but  the  variation  or 


Ficj. 


6L 


Fiq.  62, 


inequality  between  the  diameter  of  the  root,  in  proportion  to  the  dimen- 
sions of  the  space  to  be  filled  by  the  crown,  to  obtain  the  most  artistic  re- 
sults, often  requires  that  one  end  of  the  band  be  cut  on  such  an  angle  as  to 
make  a  difference  between  the  circumference  of  its  cervical  and  occlusal 
edges  when  soldered.     Fig.  61. 

While  perfectly  straight  edges  will  often  afford  sufficient  opportunity 
for  the  necessary  shaping  and  contouring  of  the  occlusal  end,  it  is  fre- 
quently desirable  and  sometimes  necessary  to  have  this  edge  of  slightly 
larger  proportions,  especially  in  bicuspids,  in  order  to  more  perfectly  and 
artistically  meet  the  requirements  of  contact  and  alignment. 

Where  the  root  is  proportionately  larger  than  the  space  to  be  filled, 
however,  the  converse  of  the  proposition  may  be  indicated,  in  order  to 
secure  and  preserve  an  alignment  of  the  occlusal  surfaces.     In  such  in- 


8o 

stances  the  edges  should  be  cut  straight,  in  order  to  facihtate  the  adapta- 
tion to  the  root,  after  which  the  circumference  of  the  occlusal  edge  may 
be  adequately  reduced. 

When  the  band  has  been  properly  cut  it  should 
Soldering.  be  annealed,  the  edges  filed  smooth,  so  as  to  approxi- 

mate evenly  when  brought  into  contact,  and  then 
given  circular  form.  Perfect  contact  of  the  edges  is  essential  to  insure  fit 
and  facilitate  soldering,  and  may  be  sustained  by  first  overlapping  and 
then  bringing  them  back  into  direct  contact.  (Fig.  62.)  This  procedure 
condenses  the  molecules  sufficiently  to  overcome  the  expansion,  when 
heated,  that  would  otherwise  cause  a  separation,  and  is  preferable  to  wir- 


ing the  outside  circumference  of  the  band 
because  the  solder  not  infrequently  pene- 
trates the  joint  and  attaches  the  wire  to  the 
gold,  which  necessitates  its  being  ground 
off  afterwards. 

When  the  edges  have  been  thus  approxi- 
mated, the  band  should  be  grasped  with 
fine-pointed  pliers  at  a  point  as  remote 
from  the  joint  as  possible,  so  that  they  may 
absorb  but  little  heat.  (Fig.  63.)  Flux 
should  be  applied,  carried  to  the  flame  and 
fused,  and  a  very  small  piece  of  solder  then 
fluxed  and  placed  immediately  over  the 
Ficj.es         joint. 

In  soldering,  it  should  be  held  in  the 
flame  so  that  each  edge  will  be  uniformly 
heated,  because  if  either  should  receive  a  preponderance  of  heat 
the  solder  would  become  attached  to  it,  and  the  addition  of  a  second 
piece  may  be  necessary.  Any  more  solder  than  is  required  to  make  the 
joint  is  oljjcctional  because  of  the  additional  stiffness  imparted  to  the 
band. 

As  it  is  desirable  to  begin  with  a  high  grade  of  solder  to  prevent  sub- 
sequent re-fusing,  and  to  admit  of  finishing  with  as  high  a  karat  as  pos- 
sible, all  bands  should  usually  be  united  with  22  karat  solder,  though 
20  karat  will  answer  the  purpose. 


S] 


For  convenience  and  comfort,  the  pliers  used  to  hold  the  work  in  the 
flame  should  possess  a  long  handle  and  thin  tapering  points.  (Fig.  64.) 
The  addition  of  platinum  points,  which  may  be  easily  attached  with  any 
hard  solder,  increases  their  usefulness,  as  such  pliers  absorb  less  heat, 
retain  their  shape  more  permanently,  and  o£ter  more  re- 
sistance to  the  attachment  of  solder. 

The   fitting   of   the   band   may   be 
fitting,  made  accurate,  easy  and  devoid  of  dis- 

comfiture, in  proportion  to  the  relation 
it  bears  to  the  shape  of  the  root  and  to  the  outline  of  its  sur- 
rounding tissue,  before  any  attempt  is  made  to  adjust  it. 
The  detail  of  requirements  in  this  connection  apply  to  any 
style  of  crown  with  a  band,  and  are, 

First — To  conform  the  band  to  the  general  shape  and 
outline  of  the  root. 

Second — To  trim  the  edge  which  is  to  pass  beneath  the 
tissue  to  closely  follow  the  cervical  curvature  of  the  process, 
and  gingival  festoon  of  the  gum,  so  that  it  will  come  in  con- 
tact evenly  and  uniforuily  at  all  points,  before  the  final 
necessary  pressure  is  applied. 

Third — To  round  and  smooth  the  edge  so  that  no  irri- 
tating influence  will  be  offered  in  forcing  it  beneath  the  gum. 

Fourth — For  the  purpose  of  convenience  and  of  avoid- 
ing any  confusion  in  adjusting  and  readjusting;  because  the 
usual  convexity  of  roots  at  this  point  faciHtates  the  adapta- 
tion of  the  stiffened  portion  of  the  band,  and  because  of 
placing  the  soldered  joint  where  it  will  be  least  conspicuous 
in  case  of  subsequent  discoloration,  as  well  as  being  most 
easily  accessible  for  reinforcement  in  the  assemblage  of 
bridgework,  the  joint  in  the  band  should  akvays  be  placed 
at  the  center  of  the  lingual  surface  of  the  root. 

A  neglect  of  any  of  these  most  essential  features  adds 
materially  to  the  difficulties  experienced  in,  and  the  possible 
discomfitures  resultant  from,  the  operation.  In  observing 
them  the  band  should  be  gently  placed  over  the  projecting 
end  of  the  root,  and  shaped  with  pliers  until  it  is  made  to 
conform  to  its  general  outline,  and  any  existing  concavities 
or  inequalities.  Its  surfaces  should  be  made  perpendicular, 
and  the  edge  then  carefully  trimmed  with  curved  pointed 
shears  until  it  meets  the  gum  line  evenly  at  all  points;  and 
then  nicely  rounded  from  the  outer  surface  with  a  fine  half- 
round  file,  until  blunt  but  smooth.    .This  minimizes  the  pos- 


F/J.G4- 


82 

sibilities  of  irritation,  without  obtaining  any  apreciable  thinness  of 
the  gold  which  would  be  objectionable  because  of  increasing  the 
liabilities  of  stretching  and  irritation. 

When  these  requirements  have  been  complied  with,  the  band  should 
be  placed  upon  the  root,  and  gently  pressed  to  place  until  the  edge  passes 
just  freely  beneath  the  tissue.  For  this  purpose  a  small  piece  of  wood  of 
convenient  size,  with  flat,  smooth  surfaces,  is  most  useful ;  and  if  properly 
used  greatly  facilitates  the  operation,  and  obviates  the  driving  of  a  band 
into  place,  which  is  entirely  unnecessary,  and  even  brutal. 

In  instances  where  a  recession  of  the  gingival  border  of  the  gum  may 
have  exposed  the  root  beyond  the  normal  outline  at  some  point,  such  as  i? 
not  infrequently  found  to  present  in  the  mesio-buccal  and  lingual  roots  of 
upper  molars,  an  extension  to  the  band  may  be  indicated  in  preference  to 
sacrificing  it  upon  other  surfaces  sufficiently  to  admit  of  thus  approaching 
the  gum  at  this  point.    This  may  be  best  accomplished  by  first  fitting  the 


band  accurately  without  regard  to  this  extension,  after  which  a  small 
piece  of  pure  gold  plate  may  be  soldered  to  the  outer  surface  of  the  band, 
and  then  trimmed  until  this  denuded  portion  of  the  root  is  covered.  When 
the  necessary  burnishing  has  been  completed,  the  adaptation  may  be  sus- 
tained by  re-enforcing  the  extension  with  a  high  grade  of  solder. 

When  the  cervical  adaptation  has  been  completed,  the  occlusal  edge 
should  be  trimmed  to  afford  accommodation  for  the  adjustment  of  a  cusp 
of  uniform  and  sufficient  depth,  and  then  filed  smooth  and  contoured. 

The  entire  artistic  effect  of  the  finished  crown, 

Contouring.  as  well  as  the  prerequisites  of  contact  and  alignment, 

depends  in  a  great  measure  upon  the  form  and  shape 
given  to  the  occlusal  end  of  the  band,  which  can  be  best  observed  at  this 
time. 

By  contouring  is  meant  the  reproduction  of  the  natural  form  and 
outline  of  the  tooth,  and  while  this  may  be  accomplished  with  solder. 


83 

after  the  cusps  have  been  united,  much  tmie,  energy  and  material  can  be 
saved,  and  far  more  artistic  results  obtained,  by  properly  shaping  the 
band  itself. 

Artistic  results  in  this  connection,  however,  are  made  possible  only 
by  a  thorough  knowledge  of  the  angles,  characteristics  and  general  forms 
of  the  natural  teeth,  the  outlines  of  which  should  be  reproduced  in  this 
edge  of  the  band.  This  may  be  done  irrespective  of  the  necessary  shape  of 
the  cervical  edge  in  its  adaptation  to  the  root,  and  without  change  of  it. 


ricj,66. 


For  contouring  purposes  various  styles  and  designs  of  pliers  are 
used,  but  as  the  shaping  should  be  done  upon  the  edge  of  the  band,  before 
the  cusp  is  attached,  all  of  the  necessary  and  artistic  results  may  be  easily 
accomplished  with  pliers,  the  beaks  of  which  are  straight,  tapering,  and 
come  closely  together,  witli  rounded  edges.  A  design  of  the  author's  for 
this  purpose  and  for  universal  use  in  crown  work  is  illustrated  in  Fig.  65, 
and,  while  some  of  the  numerous  other  designs  may  be  found  occasionally 
useful,  these   will  meet  the  general  requirements,   when  properly  used. 


84 

The  rounded  edges  and  one  smooth  beak  prevent  defacing  the  gold,  while 
the  flat  surfaces  and  one  serrated  beak,  and  the  tapering  form  for  stretch- 
ing, adds  to  their  general  usefulness. 

The  average  and  typical  requirements,  and  the  results  possible  from 
a  knowledge  of  the  form  and  outline  of  the  teeth,  and  a  skilful  manipula- 
tion of  the  pliers,  are  indicated  before  and  after  contouring  the  band  in 
Fig.  66. 

In  instances  where  the  diameter  of  the  root  after  its  preparation  is 
larger  than  the  proportionate  dimensions  of  the  occlusal  surface,  to  se- 
cure a  symmetrical  alignment  with  the  adjacent  teeth  it  may  become 
necessary  to  reduce  the  circumference  of  the  occlusal  edge  of  the  band. 
This  may  be  quite  easily  accomplished  by  cutting  numerous  slits  around 
the  approximal  and  lingual  surfaces  of  the  occlusal  edge,  and  then  draw- 
ing the  points  in  and  overlapping  them  until  the  circumference  is  suffi- 
ciently reduced.     (Fig.  67.)     These  places  may  be  afterwards  filled  in 


Fiq.67. 


with  solder  until  a  smooth  uninterrupted  surface  presents.  Although  the 
pliers  previously  mentioned  may  be  used  successfully,  a  very  convenient 
form  especially  adapted  to  this  purpose,  and  generally  useful  in  reducing 
the  size  of  either  end  of  the  band,  when  occasion  requires,  is  illustrated 
in  Fig.  68. 

After  securing  the  proper  and  desired  contour,  this  edge  should  be 
filed  smooth  and  even,  the  band  then  finally  adjusted  to  the  root,  and 
the  occluding  bite  and  impression  taken. 

The  interior  of  the  band  should  be  filled  even 

Occluding  Bite.        with    the    edge    with    wax    previous    to    taking   the 
occluding  bite.     This  facilitates  the  removal  of  the 
latter  from  the  mouth  and  its  final  adjustment  to  the  model. 

The  occluding  bite  should  always  be  taken  separately  from  the  im- 
pression, and  should  precede  it,  because  the  imprint  of  the  band  is  neces- 
sary to  admit  of  its  adjustment  to  the  model  with  the  band  in  place.   Wax 


85 

is  preferable  for  this  purpose,  because  of  the  ease  with  which  the  relation 
and  a  good  imprint  of  the  teeth  may  be  secured,  and  of  its  more  easy  and 
accurate  adjustment  to  the  model. 

In  obtaining  it  enough  wax  should  be  used  to  secure  the  imprint  of  at 
least  two  teeth  on  each  side  of  the  crown,  whenever  possible,  and  in  the 
procedure  it  should  be  definitely  ascertained  that  the  teeth  are  in  direct 
and  proper  occlusion. 

The  patient  should  then  be  instructed  to  firmly  close  the  jaw, 
and  press  the  wax  against  the  lingual  surfaces  of  the  teeth  with  the 
tongue,  when  by  compressing  it  closely  to  the  buccal  surfaces  with  the 
fingers  a  correct  and  well-defined  bite  is  readily  obtained. 

The    impression    should   ahvays  be   taken   with 

Tmprc$$iOn.  plaster,  and,  corresponding  with  the  bite,  should  in- 

clude two  or  more  adjacent  teeth,  when  present,  on 
each  side  of  the  crown.     This  is  necessary  in  order  to  prove  and  govern 


ff.66. 


the  occlusion  when  mounted  upon  the  articulator.  The  use  of  plaster  is 
essential  for  this  purpose,  because  of  the  difficulty  of,  and  uncertainty  in 
readjusting  the  band  to  its  accurate  position  in  the  impression,  when  any 
m.aterial  is  used  which  draws  perceptibly  in  removing  from  the  mouth. 
This  may  be  done  with  a  degree  of  absolute  certainty  Axlien  jilaslt-r 
is  used. 

Partial  impression  trays  of  convenient  size  for  this  purpose  are  illus- 
trated in  Fig.  69,  two  being  adapted  for  the  right  and  left  sides,  ami 
one  for  universal  use ;  the  latter,  of  course,  is  the  most  generally  use- 
ful. Because  of  the  natural  shape  of  the  teeth,  it  will  usuallv  be  found 
necessary  to  break  the  impression  in  removing  it  from  the  mouth,  which 
is  not  objectionable  if  the  parts  are  afterward  accurately  replaced.     A 


86 

convenient  tray,  recently  designed  by  Dr.  E.  L.  Townsend  to  facilitate 
such  procedure,  includes  a  separable  base  composed  of  two  smaller  trays 
with  the  dividing  line  in  the  center.  Upon  the  removal  of  the  outer  tray 
these  remain  in  place,  when  they  may  be  easily  divided  by  the  insertion  of 


the  blade  of  a  small  penknife,  which  separates  the  impression  in  two  lateral 
halves.      (^Fig.  70. ) 

When  the  parts  arc  accurately  readjusted  and  their  relation  securely 
sustained  with  melted  wax,  the  impression  should  be  then  varnished,  filled, 
separated,  the  bite  adjusted,  and  then  mounted  securely  upon  the  ar- 
ticulator.    For  the  purpose  of  facilitating  the  separation  of  the  model 


87 


Fiq.YO. 


from  the  impression,  the  latter 
should  be  first  coated  with  a  thin 
solution  of  shellac  in  alcohol,  and 
followed,  after  drying,  with  a  coat- 
ing of  very  thin  sandarac,  in  alco- 
hol. The  former  causes  a  line  of 
demarcation  of  inestimable  value  in 
separating,  and  the  latter  gives  a 
smooth,  hard  surface  to  the  model. 
Because  of 
Jlrticulators.  the  desirability 

of  obtaining  a 
degree  of  accuracy  in  articulation 
as  well  as  occlusion,  a  reproduction 
of  the  lateral  movements  of  the  jaw, 
such  as  are  made  possible  by  the  use 
of  an  anatomical  articulator,  is  al- 
most as  essential  in  crown  work 
as  it  is  in  the  construction  of  ar- 
tificial dentures. 


For  single  crowns,  however,  such  recjuirements,  while  always  desir- 
able, are  not  so  essentially  necessary,  and  in  the  absence  of  a  design  mor^' 
conveniently  adequate  for  the  purpose,  the  ordinary  crown  art'cula- 
tor  ma_v  answer.      (Fig-  /i.,) 


Processes  for  Cusp  Tormation. 


Of  the  various  methods  and  systems  for  securing  suitable  cusp  forms 
that  will  typify  the  natural  teeth,  and  meet  the  requirements  of  articula- 


tion  and  occlusion,  but   one  general   line  of  procedure  offers   absolute 
certainty  and  accuracy  in  all  cases. 

The  importance  of  true  occlusion,  as  has  been  previously  empha- 
sized, will  be  readily  apparent,  and  is  generally  conceded,  and  yet  through- 
out the  entire  evolution  of  methods  for  procuring  it,  a  system  of  stereo- 
typed typical  dies  has  predominated.  As  the  conditions  presenting  vary 
in  proportion  to  tlie  degree  of  the  normal  accuracy  of  occlusion,  position 
of  the  root,  and  its  relation  to  adjacent  teeth,  and  the  length  and  shape  of 
band  and  depth  of  cusp  required,  the  fallacy  of  expecting  a  ready-made 
form  to  closely  fit  and  approximate  the  edge  of  a  properly  contoured 
band,  and  then  articulate  and  occlude  accurately  with  the  opposing  teeth, 
is  manifest. 

Canned  Cusp  and  Special  Die  methods. 

If  these  mechanical  and  artistic  requirements  are  to  be  observed,  the 
prerequisites  of  certainty  and  accuracy  can  be  best  obtained  by  forming 


the  cusp  directly  from  an  imprint  of  the  opposing  teeth,  and  in  its  proper 
relation  to  the  band,  as  was  originally  suggested  in  primitive  form  by  Dr. 
Norman  W.  Kingsley.  While  the  detail  of  such  a  procedure  may  probably 
consume  a  little  more  time  than  some  methods,  time  is  not  the  only  factor 
to  be  considered,  except  perhaps  by  dental  laboratories;  and  the  results 
will  usually  justify  such  an  expenditure. 

When  the  models  have  been  securely  mounted 
Procedure  upon   the  articulator   (Fig.  72),  all  surfaces  of  the 

plaster  in  close  proximity  to  the  band  should  be  var- 
nished with  a  thin  coating  of  collodion,   sandarac  or  silex.     The  band 


Sq 


should  now  be  filled  with  thin,  well  mixed  plaster,  into  which  the  occusal 
surfaces  of  the  opposing  teeth  are  then  imprinted  by  firmly  closing  the 
articulator.  (Fig.  73.)  The  reproduction  of  adjacent  teeth  in  the  model 
serves  to  sustain  and  prove  the  proper  occlusion.  When  this  has  become 
sufficiently  crystallized,  the  articulator  should  be  opened,  and  the  band, 
with  its  plaster  contents,  detached  from  the  model  in  such  manner  as  to 
preserve  its  definite  outline  and  relation.     The  surplus  plaster  around  the 


Fi<^.  73. 

outer  edge  of  the  band  should  be  removed  with  the  sharp  blade  of  a 
small  penknife,  which  leaves  the  remaining  contents  somewhat  crude  and 
inartistic  in  outline,  but  accurate  in  occlusion.  (Fig.  74.)  An  artistic 
effect,  in  proportion  to  the  degree  of  skill  possessed  by  the  operator,  may 
be   obtained   by   inserting  the   grooves   and  pits   of   the   typical   outline 


Fic^.74, 


Ficj,  15, 


of  the  tooth,  which  may  be  done  without  perceptible  change  to  the  occlu- 
sion. In  fact,  the  latter  is  thus  improved  because  of  the  formation  and 
separation  of  the  cusps.      (Fig.  75.) 

While  modeling  compound,  mouldine  and  wax  are  sometimes  em- 
ployed for  the  formation  of  cusps,  the  use  of  any  of  them  is  not  so  reliable 
as  plaster,  because  of  the  tendency  to  flake  in  carving,  or  of  the  suscepti- 
bility to  change  form  in  the  subsequent  process  of  securing  the  mould  for 


go 

the  die,  or  for  casting.  In  the  process  of  carving,  it  is  not  altogethei 
necessary  that  the  correct  anatomical  outHne  of  the  tooth  should  be  repro- 
duced, but  only  to  typify  it  sufficiently  to  designate  the  tooth  it  represents. 
This  may  be  easily  accomplished  by  inserting  the  grooves  deep  enough  to 
separate  the  cusps,  and  typical  enough  in  outline  to  distinguish  the  right 
from  the  left,  and  the  upper  from  the  lozver.     (Fig.  76.) 

In  the  reproduction  of  the  plaster  cusp  in  gold,  two  methods  of  pro- 
cedure are  employed,  by  means  of  which  plate  gold  may  be  conformed  by 
swaging  between  dies,  or  a  solid  cusp  produced  by  casting. 

Because  of  the  possibilities  for  securing  a  more 
Swaged  Cusps.        distinct  and  definite  reproduction  of  the  outline;  of 
the  time  saved  in  adjusting  and  adapting  the  cusp  to 
the  band,  and  of  securing  adequate  thickness  of  cusp  by  subsequent  re 


RIGHT  LEPT 


RIGHT  LEFT  RIGHT  LEFl 

/y^.  76. 


enforcement  with  solder,  the  swaged  method  is  usually  preferable. 
For  this  procedure  the  plaster  cusp  should  be  trimmed  away  uniformly 
around  its  peripheral  border,  until  the  edge  of  the  band  is  exposed.  This 
reduction  in  size  allows  for  the  thickness  of  gold  forming  the  cusp,  and 
renders  possible  a  perfect  approximation  of  the  edges  of  cusp  and  band. 
If  not  observed,  the  cusp  will  be  as  much  larger  than  the  band  as  its 
thickness,  which  will  require  the  use  of  solder  in  securing  a  smooth  sur- 
face in  its  subsequent  attachment. 

A   moulding    ring    (Fig.  yy)    should   be   filled 
mould.  even  and  flush  to  its  edges  with  moukline,  into  the 

center  of  one  surface  of  which  the  plaster  cusp,  after 
being  dusted  with  lycopodium  or  soapstone,  should  be  firmly  imprinted 
just  deep  enough  to  secure  the  outline  of  the  exposed  edge  of  the  band. 
The  mouldine  should  be  packed  closely  against  the  band  around  its 
circumference,    and    the    band    and    plaster    cusp    removed    from    the 


mould.    This  should  be  dusted   with  lycopodium  and  the  dies   secured. 

The  most  useful  and  convenient  system  of  dies 

Dies.  may  be  secured  by  placing  a  casting  cup  (Fig.  78), 

which  has  a  small  perforation  through  the  center  of 

the  base,  over  the  mould,  and  casting  a  cusp-button  of  pure  tin  or  Watt's 

metal  (Fig.  79).     After  cooling,  the  button  should  be  detached  from  the 

cup  with  a  small  knife-blade,  and  placed  upon  a  smooth  surface  of  mould- 


Fiqm. 


Ficf.  80. 


Ffj.81. 


Fiq.82. 


ine,  in  the  moulding  ring,  then  dusted  freely  with  lycopodium,  and  the 
rubber  ring  adjusted  for  the  purpose  of  securing  the  counter-die  (Fig.  80), 
which  is  poured  with  fusible  alloy. 

A  higher  fusing  metal  than  any  of  the  fusible  allocs  is  necessary  for 
casting  the  cusp-button  in  order  to  preclude  the  probability  of  melting  it 
in  securing  the  counter-die. 


92 

In  the  process  of  forming  the  cusp  with  these  dies  (Fig.  8i),  the 
swaging  should  be  done  in  the  counter-die  by  the  use  of  an  ingot  of  lead, 
or  a  large  buckshot,  until  closely  adapted,  after  which  the  surplus  gold 
should  be  cut  away  and  the  cusp-button  used  for  the  final  swaging  only,  to 
bring  out  the  finer  lines.  These  cusp-buttons  may  be  preserved  and  found 
useful  wherever  occasion  admits  of  the  use  of  ordinary  and  typical  dies, 
such,  for  instance,  as  the  absence  of  occluding  and  adjacent  teeth. 

Another  method  somewhat  more  simple  is  to  secure  the  mould  as 
indicated,  and  then  adjust  the  rubber  ring  and  pour  the  die  of  fusible 
alloy.  The  surface  is  then  dusted  with  lycopodium  or  coated  with  a  solu- 
tion of  whiting  in  alcohol,  the  rubber  ring  readjusted,  and  a  counter-die 
of  the  same  metal  and  dimensions  secured.     (Fig.  82.) 

While  this  will  answer  the  purpose,  if  the  swaging  is  done  in  similar 
manner,  the  tendency  of  stretching  and  probability  of  tearing  the  gold 


will  be  increased,  especially  if  the  cusp  is  very  deep,  because  of  the  diffi- 
culty of  swaging  and  conforming  gold,  or  any  metal,  to  any  given  or  de- 
sired shape  between  two  surfaces  of  like  and  equal  resistance,  in  which 
respect  lies  the  advantage  of  the  former  method. 

In  the  process  of  swaging,  the  surfaces  of  the  dies 
Swagiltg.  should  be  oiled  to  facilitate  the  procedure,  and  pre- 

vent sticking.  A  convenient  method  of  preventing 
the  defacing  of  the  gold  is  to  stretch  a  piece  of  rubber  dam  over  it  before 
driving  into  the  counter  die.  This  also  avoids  any  coating  of  the  die  metal 
from  adhering  to  the  surface  o^  the  gold.  The  chances  of  tearing  the  gold 
may  l)e  reduced  to  a  minimum  by  first  swaging  a  few  layers  of  heavy 
tinfoil  covered  by  the  rubber  dam.  This  slightly  compresses  the  metals 
and  affords  space  for  the  gold  between  the  two  surfaces  of  the  dies, 
and  it  should  first  be  carefully  worked  down  into  the  counter  die  with 


93 


a  small  blunt-pointed  piece  of  wood.  The  gold 
used  should  be  of  the  same  karat  and  color  as  the 
band,  and  of  28  gauge  thickness,  as  it  is  to  be 
subjected  to  considerable  stretching.  It  should 
be  cut  somewhat  larger  than  the  diameter  of  the 
cusp  to  be  formed,  and  frequently  annealed  dur- 
ing the  process ;  and  a  round  or  disk-sliaped  piece 
of  plate  will  yield  more  readily  to  the  desired 
conformation  between  the  dies,  with  less  ten- 
dency to  overlap  at  the  angles ;  and  all  unneces- 
sary surplus  should  be  removed  before  the  final 
swaging.  Steady  and  uniform  pressure,  such  as 
would  result  from  the  use  of  a  press  of  adequate 
power,  would  be  productive  of  better  results,  in 
the  absence  of  which  a  heavy  hammer  and  direct 
blow  will  answer. 

When  the  swaging  has 

JIdjUSling  Cusp.  been  completed,  the  edge  of 
cusp  should  be  carefully 
trimmed  down  to  the  line  marking  its  point  of 
contact  with  the  band,  which  should  be  outlined 
in  the  gold.  This  point  can  be  approached  with 
small  curved  crown  shears,  but  the  final  trimming 
should  be  done  with  a  fine  flat-surface  gold  file, 
and  may  be  best  and  more  uniformly  accom- 
plished by  holding  the  file  steady  and  carrying 
the  cusp  backward  and  forward  over  its  surface. 
The  plaster  cusp  should  then  be  removed  from 
the  band,  and  the  latter  adjusted  to  place  on  the 
articulator.  After  filling  the  interior  of  the  band 
with  wax  to  sustain  the  cusp,  it  should  be  con- 
secutively trimmed  and  tried  to  place  until  the 
edges  approximate  evenly,  and  the  desired 
occlusion  is  obtained  and  proven  by  the  firm 
closure  of  the  articulator.     (Fig.  83.) 

The    necessary    re-en- 

SOldcrlng  Cusp.  forcement  of  the  cusp  to 
fortify  it  against  constant 
and  continued  attrition  may  be  done  with 
solder  simultaneously  with  its  attachment  to 
the  band,  although  no  objection  is  offered  to 
filling   the    cusp    with    solder   previous    to    its 


94 

subsequent  attachment  if  done  with  the  same  karat  that  would  be 
indicated  and  used  in  the  joint.  During  the  process  of  solder- 
ing, the  relation  between  cusp  and  band  should  be  securely  sus- 
tained. This  can  be  best  accomplished  by  the  use  of  automatic  pliers  de- 
signed for  the  purpose  as  indicated  in  Fig.  84,  the  use  of  wire  being  objec- 
tionable for  the  same  reasons  previously  mentioned  in  connection  with 
soldering  the  band. 

The  parts  should  be  treated  to  the  acid  bath,  freely  washed  with  water, 
and  adjusted  in  the  pliers.  Flux  should  then  be  applied  to  the  joint  and 
fused,  and  the  parts  united  with  22  or  20  karat  solder.  The  necessary 
re-enforcement  may  be  obtained  with  18  karat  solder.  In  case  of  a 
perforation  of  the  gold  as  a  result  of  swaging,  the  same  should  be  first 


pi(],es. 


filled  with  foil,  when  no  trouble  will  be  experienced  in  covering  it  over 
or  filling  it  in  with  solder. 

When    the    soldering   has    been    completed,    the 

Titlisbing.  crown   should  be  again  treated  to  the  acid  bath  to 

dissolve  remaining  borax,  then   dressed  down  with 

carborundum  stones  and  disks  in  the  engine,  and  finally  polished  on  the 

lathe. 

While  no  special  or  particular  advantage  is  af- 
Solld  €ast  €u$t)$.  forded  by  the  formation  of  a  solid  or  cast  cusp, 
excepting  that  the  presentation  of  a  faulty  or  inaccu- 
rate occlusion  may  be  remedied  by  grinding  freely  without  exposing  the 
solder,  yet  many  prefer  to  pursue  this  method.  When  such  procedure 
seems  desirable,  the  plaster  cusp,  after  carving,  should  be  left  Hush  and 
continuous  with  the  outside  edge  of  the  band. 

The  moulding  ring  should  be  filled  with  mouldine,  and  the  mould  of 
the  cusp  secured  on  a  line  with  the  edge  of  the  band.     This  should  then 


95 

be  placed  over  the  Bunsen  burner  and  allowed  to  remain  until  the  mould- 
ine  becomes  hard.  Asbestos  of  adequate  thickness  to  accommodate  the 
depth  of  the  cusp  may  also  be  used  for  the  mould  by  saturating  it  with 
water  until  a  suitable  imprint  of  the  plaster  cusp  can  be  made  in  it,  after 
which  it  should  be  dried  in  the  same  manner.  Scrap  gold  of  sufficient 
quantity,  sparingly  fluxed,  should  be  fused  in  the  mould,  and,  when 
molten,  may  be  easily  cast  by  quickly  pressing  it  into  the  matrix  with  a 
smooth  surface  of  carbon  or  steel  large  enough  to  cover  the  entire  area  of 
the  cusp.  (Fig.  85.)  The  principal  objection  offered  to  this  method  is 
the  time  ordinarily  required  to  trim  and  file  the  surface  until  a  perfect 
approximation  with  the  band,  and  the  necessary  requirements  of  occlu- 
sion are  obtained.    Such  cusps  may  also  be  cast  by  Dr.  Taggart's  method. 

Cusp  Tormation  witbout  models. 

The  same  detail  of  procedure  is  applicable  to  the  formation  of  cusps 
without  the  use  of  models  or  articulator.  The  results,  however,  while 
perhaps  occasionally  as  artistic,  are  not  so  accurate,  because  no  guide  for 


obtaining  the  correct  length  of  cusps  is  present,  and  no  opportunity  is 
afforded  for  proving  the  articulation  and  occlusion  in  the  final  adjust- 
ment and  attachment  of  the  cusps  to  the  band,  unless  it  be  done  directly 
in  the  mouth. 

When  the  employment  of  such  a  procedure  may  seem  mdicated,  of 
when  it  may  be  desirable  or  necessary  to  complete  the  crown  at  a  single 
sitting,  the  band  in  position  on  the  root  may  be  filled  with  a  sufficient 
quantity  of  plaster,  in  the  plastic  state,  or  with  modeling  compound,  and 
the  teeth  closed  directly  into  it.  After  thoroughly  hardening  it  should  be 
removed,  the  surplus  trimmed  away  even  with  the  band,  and  the  desired 
and  typical  shape  and  form  then  given  it  by  carving,  as  is  consecutively 
illustrated  in  Fig.  86,  when  the  dies  or  mould  may  be  obtained  in  the 
manner  outlined,  and  the  crown  finished,  as  indicated. 

JisWs  Crown  Swaging  DciJicc. 

Ash's  crown  swaging  device,  which  consists  of  a  cylinder  and 
plunger,  and  a  soft  rubber  or  hydraulic  pad,  will  be  found  quite  useful 


96 

for  swaged  cusps,  because  of  eliminating  the  necessity  for  the  use  of  any 
counter-die,  or  of  swaging  between  two  surfaces  of  metal,  and,  by  pre- 
venting any  rebound,  displacement  or  defacing  of  the  gold  during  the 
process. 

In  its  use  the  mould  from  which  the  die  is  secured  must  be  obtained 
in  a  moulding  ring  of  suitable  dimensions,  to  render  it  of  a  size  corre- 
sponding to  the  interior  diameter  of  the  cylinder.  These  are  included  in 
an  outfit  suggested  by  Dr.  E.  G.  Christiansen,  of  Dremmen,  Norway, 
and  manufactured  by  C.  Ash  &  Sons. 


Ficj.QT, 


When  the  die  has  been  secured  with  fusible  alloy  it  should  be  placed 
in  the  cylinder,  the  gold  annealed  and  placed  in  position,  and  the  sofi 
rubber  or  hydraulic  pad  then  inserted. 

The  plunger  is  then  adjusted,  and,  upon  being  driven  into  the  cylin- 
der, results  in  the  swaging  being  easily  and  quickly  accomplished,  witli- 
out  danger  of  tearing  or  defacing  the  gold. 

If  the  cusp-button  method  of  dies  has  been  employed,  and  the  button 
afterward  used  only  to  bring  out  the  finer  and  more  definite  lines,  the 
swaging  may  be  done  in  the  counter  die  in  the  same  manner 
(Fig.  87). 


97 


Die  ana  Dic^Plate  metDods. 

The  advent  of  the  die  and  the  die-plate  systems  was,  primarily,  the 
outcome  of  a  desire  for  obtaining  more  natural  and  artistic  results  in  the 
process  of  cusp-formation  than  was  then  possible  by  pursuing  the  primitive 
method.  Originally,  efforts  in  this  line  were  confined  to  soldering  a  flat 
surface  of  gold  to  the  band,  and  then  building  the  cusps  at  various  points 
upon  this  surface  with  small  globules  of  scrap  gold,  or  pieces  of  triangu- 
lar platino-iridium  wire,  attached  with  solder;  or  with  solder  alone,  and 
subsequently  grinding  to  the  desired  form  and  occlusion. 

While  many  of  these  somewhat  crude,  inaccurate  and  inartistic 
effoi^ts  were  successful  from  the  standpoint  of  serviceabilit}^  and  useful- 
ness, the  introduction  of  dies  soon  followed.  These  were  designed  to 
serve  as  a  means  of  securing  more  artistic  results,  and  as  a  time-saving 

procedure. 

The  first  productions  in  this 
Individual  Dies.  line  were  individual  dies,  ob- 
tained directly  from  the  natural 
teeth.  For  this  purpose  suitable  extracted  teeth  were 
.selected,  and  mounted  in  a  base  of  plaster.  This  was 
then  trimmed  to  favorable  shape  for  securing  a  mould 
in  sand,  from  which  a  casting  was  made  of  zinc. 

Plate  gold  was  then  swaged  to  conform  with  the 
outlines  oi  the  natural  cusps  by  driving  the  die  into  a 
smooth  surface  of  lead,  or  an  old  discarded  counter-die. 
This  method  was  productive  of  so  great  a  degree 
of  improvement  over  the  former  procedure  as  to  sub- 
sequently induce  the  supply-houses  to  manufacture 
these  dies  in  sets  of  various  numbers,  and  made  of 
brass  in  order  to  be  more  permanent  and  indestructible 
(Fig.  88). 

Because  of  the  immediate  necessity  for  a  suita- 

DiC-PlatCS.  ble  counter-die,  and  of  the  advantage  of  combining 

a  larger  variety  of  cusp-forms  into  more  convenient 

and    compact    order,    the    introduction    of    the    die-plate    was    a    natural 

sequence. 

These  comprise  various  numbers  of  cusp-iiKiulds  in  a  brass  or  steel 
casting.  In  their  use  the  swaging  is  easily  and  quickly  accomplished  by 
driving  the  disk  of  gold  into  the  mould  selected  to  best  approach  the  re- 
quirements, with  an  ingot  of  lead  or  alloy  of  lead  and  tin.  Ingots  for  the 
purpose  may  be  previousl}-  cast  in  any  quantity,  and  of  adequate  and  con- 
venient sizes  by  the  use  of  a  hub-mo  aid  designed  for,  and  usually  accom- 
panying, the  die-plate  (Fig.  89).     Ordinary  buckshot,  however,  are  easy 


Fig .  88 ^ 


98 

to  procure,  and,  if  of  suitable  size,  will  answer  the  purpose  nicely.  The 
steel  plates  may  also  be  thus  employed,  or  may  be  used  to  produce  solid 
cusps  by  driving  an  ingot  of  scrap  gold  into  the  mould  selected. 

While  these  plates  are  still  in  common  use  their  value  and  range 
of  application  increases  in  proportion  to  the  number  and  variety  of  cusp- 
forms  contained,  and  their  limitations,  of  course,  decrease  in  inverse 
ratio. 

In  their  use  the  mould  should  be  selected  which 

Hpplication.  best  represents  the  individual  tooth  to  be  crowned, 

and. meets  or  approaches  the  size  of  the  band.     The 

requirements  of  occlusion  must  be  secured  in  the  fitting  and  adjustment 

of  the  cusps  to  the  band,  which  can  only  be  observed,  of  course,  after 

swaging  the  cusps. 

With  cusps  formed  by  any  die-plate  system  or 

HdjUSting  method  the  best  and  most  accurate  relation  can  be 

Witl)  models.  secured  with  models  mounted  upon  the  articulator. 

Opportunity  is  thus  afforded  for  trimming  the  band 


or  the  cusps,  until  their  approximation  admits  of  a  favorable  occlusion, 
which  can  be  noted  upon  the  lingual  as  well  as  the  buccal  surfaces. 

More  perfect  occlusion  may  often  be  obtained  by  depressing  the 
cusps  with  a  blunt  instrument,  or  piece  of  wood ;  or,  if  necessary,  by 
building  up,  wherever  indicated,  with  a  high  grade  of  solder.  Small 
globules  of  scrap  gold  or  pieces  of  gold  or  platinum  wire  facilitate  such 
procedure  by  affording  a  guide  as  to  the  desired  formation  and  location, 
and  by  requiring  the  control  of  less  solder  in  their  attachment. 

When  the  requirements  of  occlusion  have  been  thus  observed,  an 
effort  should  be  made  to  closely  approximate  the  edges  of  cusps  and 
band.  This  may  be  done  by  adjusting  the  one  to  the  other  with  pliers, 
if  care  be  exercised  so  as  not  to  distort  the  shape  of  the  band  and  destroy 
its  contact  and  alignment.  Any  necessary  filling  in  or  subsequent  con- 
touring may  be  done  with  solder  in  the  final  attachment.  Where  a  con- 
siderable space  exists  between  the  two  portions,  the  process  of  soldering 
is  facilitated  by  burnishing  a  piece  of  thin  pure  gold  plate,  or  packing 
foil  gold  into  such  spaces. 


99 

In  emergencies,  or  where  it  may  seem  desirable 
HdlUSflng  to  complete  the  crown  without  models,  and  secure 

Without  models.  the  adjustment  in  the  mouth,  the  fitting  may  be 
facilitated  by  filling  the  interior  of  the  band  with 
wax  to  temporarily  sustain  the  cusps  during  the  process.  When  the 
parts  have  been  approximated,  a  more  perfect  occlusion  may  often  be 
obtained  by  tacking  the  cusps  to  the  band  at  one  point  with  a  very  small 
bit  of  solder,  and  then  replacing  the  crown  and  having  the  opposing 
teeth  closed  firmly  into  it,  after  which  the  soldering  may  be  completed, 
and  the  necessary  reinforcement  given.  If  the  requirements  are  particu- 
larly difficult,  the  process  may  be  further  facilitated  by  swaging  the  cusps 
of  30  gauge  pure  gold.  This  is  so  much  more  yielding  and  will  offer  so 
little  resistance  to  the  closure  of  the  teeth  into  firm  occlusion,  as  to  insure 
moderately  accurate  results,  but  such  cusps  should  be  attached  with  a 
very  high  grade  of  solder,  as  the  extreme  softness  of  the  gold  will  soon 
result  in  its  exposure.  This  procedure  is  equally  applicable,  of  course,  to 
the  adjustment  of  cusps  formed  by  any  system  or  method  employed, 

1)Ollind$wortb  System. 

Ihe  great  variation  in  the  size,  shape  and  depth  of  cusps  necessary 
to  meet  or  approach  the  requirements  of  this  style  of  crown  construction, 
and  the  previous  absence  of  any  system,  or  definite  detail  in  the  work, 
resulted  in  the  introduction  of  the  Hollingsworth  System,  devised  by  Dr. 
J.  G.  Hollingsworth. 

This  was  the  first  system  embracing  a  detailed  line  of  procedure  in 
the  construction  of  gold  crowns,  and  because  of  including  a  large  variety 
and  selection  of  typical  forms,  of  its  simplicity,  and  of  being  so  great  an 
improvement  over  former  methods,  it  is  much  used. 

It  comprises  about  two  hundred  typical  occlusal  forms  in  the  shape 
of  cusp-buttons,  and  a  good  selection  of  moulds  of  the  buccal  surfaces  of 
bicuspids  and  molars,  and  of  the  labial  and  lingual  surfaces  of  the  anterior 
teeth. 

Those  for  the  buccal  surfaces  of  bicuspids  and  molars  are  designed 
for  the  purpose  of  securing  a  more  artistic  shape  in  these  surfaces  of  the 
band  by  swaging,  or  for  gold  reproductions  of  the  entire  tooth.  For  the 
former  purpose,  however,  such  procedure  by  any  system  is  unnecessary, 
because  of  the  time  consumed,  and  of  the  possibilities  for  otherwise,  and 
more  quickly  securing  a  proper  and  equally  artistic  shape.  While  such 
moulds  may  often  be  found  useful  for  obtaining  all  gold  dummies  for 
bridge  construction,  those  for  the  anterior  teeth  are  practically  useless, 
because  of  the  limited  indications  for  the  application  of  such  crowns. 

The  variety,  form  and  convenient  shape  of  the  cusp-buttons,  how- 


lOO 

ever,  affords  for  them  a  more  or  less  extensive  range  of  application  and 
usefulness.  They  are  made  of  a  metal  which  is  moderately  indestructible, 
and  are  used  only  for  the  purpose  of  forming  the  die  for  the  subsequent 
conformation  of  the  gold  by  swaging,  or  for  securing  the  mould  in  asbes- 
tos for  the  purpose  of  obtaining  solid  cast  cusps,  as  previously  indicated. 

The  convenient  size  of  the  cusp-buttons  possesses  the  advantage  of 
facilitating  the  selection  of  the  one  most  favorable  to  meet  the  require- 
ments, which  may  be  accomplished  by  trying  to  place  upon  the  band,  on 
the  articulator,  or  in  the  mouth. 

Aside  from  the  forms,  the  system  consists  of  a  steel  moulding  plate 
and  suitable  rubber  moulding  rings. 

When  the  cusp-button  which  best  represents  the 

Jlpplication.  tooth,  and  meets  the  requirements  of  occlusion  and 

approximation  with  the  edge  of  band,  has  been 
selected,  it  should  be  deposited  upon  the  moulding  plate,  and  the  rubber 
ring  placed  around  it.  Fusible  alloy  should  be  then  melted  and  poured 
into  the  ring.  In  pouring,  it  should  be  directed  immediately  upon  the 
center  of  the  cusp-button,  in  order  to  prevent  an  imperfect  die,  or  one 
not  entirely  surrounded  with  metal. 

When  the  fusible  alloy  has  crystallized,  it  should  be  cooled  by  dip- 
ping into  water,  and  the  rubber  ring  then  detached.  The  cusp-button 
may  be  then  easily  separated  by  gently  tapping,  and  replaced  in  the  tray, 
and  the  die  is  ready  for  the  swaging  of  the  gold.  This  is  accomplished 
in  the  manner  indicated,  by  the  use  of  a  buckshot,  or  ingot  of  lead,  driven 
to  place  with  a  swaging  hammer,  after  which  the  surplus  may  be  trimmed 
away,  and  the  cusps  finally  adjusted  to  proper  relation  with  the  band  and 
occlusion,  and  then  soldered. 

The  use  of  these  cusp-buttons  offers  the  additional  advantage  of 
affording  opportunity  for  modifying  or  improving  the  occlusion  when 
indicated,  by  building  the  cusps  up  with  mouldine  at  the  desired  points, 
and  to  the  desired  depth,  before  pouring  the  die.  Also,  in  cases  where 
ihc  band  may  he  so  short  as  to  require  a  deeper  cusp,  this  may  be  easily 
secured  by  raising  the  cusp-button  on  the  moulding  plate  with  a  base  of 
mouldine  of  sufficient  thickness  to  make  up  the  deficiency  in  depth,  and 
trimmed  to  closely  follow  the  outline,  before  pouring  the  die. 

m\mr$  system. 

( Jnc  of  the  most  modern  inventions  in  die-])latcs,  and  processes'of 
swaging,  and  one  possessing  some  new  and  good  features,  has  been  re- 
cently  introduced   in  Millctt's   .System. 

This  consists  of  a  large  die-plate  com])rising  about  four  hundred 
raised  moulds  of  cusp-forms,  and  buccal  and  labial  surfaces,  syste.mati- 


lOI 

cally  arranged  in  sizes,  and  for  each  side  of  the  mouth,  and  the  necessary 
apparatus  for  swaging. 

While  the  forms  are  similar  in  size  and  shape  to  those  of  the  Hol- 
lingsworth  System,  the  die-plate  offers  a  greater  range  of  application  in 
a  larger  variety  for  selection,  and  the  advantage  of  each  one  being  an 
integral  part  of  the  plate,  which  overcomes  the  possibility  of  the  disar- 
rangement or  loss  of  any  of  them. 

This,  together  with  the  method  of  securing  the  die,  and  the  process 
of  swaging,  without  doubt  aft'ords  greater  simplicity  and  quicker  results, 
but  the  important  feature  of  not  being  able  to  adjust  the  cusp-forms  to 
position  on  the  band,  as  an  aid  in  their  proper  selection,  is  a  disadvantage. 

The  apparatus  for  swaging  includes  a  cylinder  and  plunger,  and  a 
bed-plate  and  soft  rubber  block,  which  are  similar  to  Ash's  crown  swag- 
ing outfit. 

The  bed-plate   is   designed   for  the   purpose  of 

Jlpplication.  holding   a    sufficient    quantity    of   ordinary    sealing- 

wax  to  secure  a  die  of  any  of  the  individual  moulds, 
and  fits  accurately  in  the  cylinder. 

The  sealing-wax  contained  in  the  bed-plate  is  softened  by  passing 
through  a  flame,  and  then  pressed  firmly  over  the  form  selected  to  be 
duplicated  in  gold,  and  which  is  calculated  to  be  the  nearest  approach  to 
the  requirements. 

This  gives  an  accurate  impression  of  the  form,  in  the  wax,  which, 
after  chilling  in  cold  water,  is  sufficiently  hard  to  answer  the  purpose  of 
a  die. 

This  is  placed  in  the  cylinder,  the  gold  annealed  and  placed  on  top 
of  it,  the  soft  rubber  block  inserted,  the  plunger  placed  over  all,  and  the 
swaging  accomplished  by  driving  the  plunger  into  the  cylinder  with  a 
moderately  heavy  swaging  hammer. 

In  cases  where  a  deeper  cusp-form  is  desired,  or  necessary,  a  rim  of 
warm  sealing-wax  may  be  moulded  around  the  edge  of  the  imprint  until 
sufficient  increase  of  depth  is  obtained,  before  swaging.  Where  a  more 
shallow  reproduction  is  indicated,  the  sealing-wax  may  be  trimmed  or 
pared  dow^n  accordingly ;  or,  if  the  summits  of  one  or  more  of  the  indi- 
vidual points  or  cusps  need  to  be  made  more  pronounced,  the  die  may  be 
deepened  at  such  points  witli  a  sharp  1nu-  or  suitabl\-  sliapctl  cultnig  in- 
strument. 

Cowrv  System. 

This  system,  devised  by  Dr.  H.  S.  Lowry,  departs  from  other  methods 
where  moulds  are  used,  and,  like  the  original  die-plates,  comprises  the 
actual  dies  to  be  used  in  the  process  of  swagmg. 


I02 

The  improvement  lies  in  the  more  extensive  selection,  and  the  sup- 
plemental trial  caps  which  represent  the  exact  size  and  formation  of  the 
dies. 

The  dies  are  individual  in  character,  made  of  a  practically  indestruc- 
tible metal,  and  each  one  is  numbered.  The  trial  caps  are  numbered  cor- 
responding with  the  dies  of  which  they  are  counterparts,  and  are  pro- 
vided with  a  projecting  stem,  which  facilities  holding  and  handling 
them  in  their  adjustment  to  the  band,  in  the  process  of  selecting  the  one 
best  suited  to  the  requirements. 

The  system  includes  a  moderately  good  selection  of  about  sixty  dies 
of  cusp-forms ;  and  a  smaller  number  of  the  buccal  surfaces  of  bicuspids 
and  molars,  and  the  labial  surfaces  of  the  anterior  teeth,  with  correspond- 
ing complement  dies,  together  with  a  "stamper"  for  swaging,  and  solder- 
ing pliers  for  general  use. 

The  trial  caps  are  adjusted  to  position  on  the 

JFIpplication.  band,  until  a  selection  is  made  of  the  one  which  best 

meets  the  requirements.  The  number  of  this  is 
noted,  and  the  corresponding  die  selected.  The  surface  of  the  die  should 
then  be  slightly  oiled,  and  the  gold  cut,  annealed,  and  placed  over  it,  and 
then  adjusted  to  position  in  the  "stamper."  A  buckshot  or  piece  of  lead 
of  suitable  proportions  should  then  be  placed  upon  the  gold,  and  the 
plunger  of  the  "stamper"  brought  in  contact. 

The  plunger  is  held  quite  securely  in  any  position  by  means  of  fric- 
tional  contact,  which  facilitates  the  swaging  in  preventing  the  rebounding 
of  the  die,  or  the  slipping  or  moving  of  the  gold  or  lead  during  the  pro- 
cess of  driving  it  down  by  the  use  of  a  swaging  hammer. 

A  special  die,  containing  two  depressions  of  different  sizes,  is  pro- 
vided for  improving  the  occlusion  when  indicated,  by  lengthening  or 
deepening  the  cusps  at  any  desired  point.  After  the  cusps  have  been 
swaged,  the  point  to  be  raised  or  deepened  should  be  placed  over  the  hole, 
and  further  swaged  to  the  necessary  extent  by  the  use  of  a  blunt  piece  of 
wood  of  suitable  size. 

Baira  system. 

Another  recent  device  in  this  line  is  the  system'  and  method  designed 
by  Dr.  W.  H.  Baird. 

This  consists  of  a  heavy  pair  of  swaging  pliers,  with  parallel  jaws, 
one  of  which  is  grooved  to  admit  of  slides  which  support  the  dies. 

The  dies  are  raised  and  individual  in  character,  made  of  a  compara- 
tively indestructible  metal,  and  include  about  two  hundred  and  fifty  mod- 
erately good  forms.     These  comprise  a  good  selection  of  cusp-forms,  and 


103 

a  proportionate  number  of  the  buccal  surfaces  of  bicuspids  and  molars, 
and  the  labial  and  lingual  surfaces  of  the  anterior  teeth. 

When  the  selection  of  the  form  calculated  to 

Application.  best  meet  the  requirements  has  been  made,  it  is  then 

placed  in  position  on  the  slide,  and  the  latter  ad- 
justed to  the  grooves  in  the  pliers. 

The  gold  is  then  annealed,  placed  upon  the  die,  and  covered  with  a 
pad  of  soft  rubber,  or  piece  of  sheet  lead  of  adequate  thickness  (about  3-16 
of  an  inch),  and  dimensions,  to  serve  as  a  counter-die.  The  pliers  are 
then  closed  and  held  together  with  sufficient  firmness  to  prevent  any  re- 
bound during  the  process  of  swaging,  which  is  accomplished  with  a 
hammer. 

The  flat  base  to  each  die  precludes  any  opportunity  for  accurately 
adjusting  to  the  band,  in  making  the  selection ;  and  the  system  affords 
no  provision  for  altering  the  cusp  reproductions  to  more  perfectly  meet 
the  requirements  of  occlusion,  depending  upon  the  variety  and  general 
application  of  the  dies  for  this  purpose. 

Seamless  Ittetboa. 

The  seamless  method  comprises  forming  the  entire  crown  with  one 
piece  of  gold,  by  swaging,  and,  while  many  systems  for  this  particular 
style  of  construction  have  been  devised,  and  are  used,  a  close  observation 
of  the  relative  advantages  and  disadvantages  as  compared  with  the  sec- 
tional method  fails  to  afford  any  real  or  practical  evidences  of  special 
merit  in  this  process. 

It  is  claimed  by  those  using  and  advocating  this  method  that  a  closer 
reproduction  of  the  natural  tooth  form  is  possible,  and  that  greater  oppor- 
tunities for  more  pronounced  contouring  are  afforded,  from  which  asser- 
tions it  is  deduced  that  more  artistic  results  may  be  obtained. 

As  such  results  from  any  method  of  procedure,  however,  are  cqiiallv 
dependent  upon  the  skill,  ability  and  conscientious  efforts  of  the  operator, 
and,  as  the  presence  of  a  joint  between  cusp  and  band  is  in  no  way  objec- 
tionable if  the  prerequisites  previously  mentioned  have  been  observed,  any 
actual  or  practical  foundation  for  such  a  claim  is  scarcely  apparent. 

If  it  were  still  necessary  to  depend  upon  a  limited  selection  of  cusp 
forms,  which  were  difificult  to  adapt  to  the  average  properly  contoured 
band  without  the  use  of  considerable  solder  and  much  filling  in,  some  ad- 
vantage might  be  possessed  by  a  method  whidi  would  afford  a  smooth 
continuous  crown,  but,  in  view  of  the  possibilities  already  outlined  in  this 
connection,  the  real  value  of  the  seamless  method  will  doubtless  always 
remain  more  appreciable  to  the  "dental  laboratories,"  and  others  commer- 
cially interested,  than  to  the  average  practitioner  of  ordinary  skill. 


104 

A  summary  of  the  possible  advantages  of  this 

BiVMtHQtS,  method  presents  but  two  special  features  :    First,  the 

opportunities  for  obtaining  contour,  and,  second,  the 
absence  of  a  joint  or  seam  of  solder  at  any  point. 

The  first  feature  needs  no  consideration,  because,  as  has  been  pre- 
viously asserted,  the  possibilities  of,  and  opportunities  for,  contouring, 
are  not  entirely  dependent  upon  the  process  employed,  and  in  no  way  ex- 
ceed those  offered  by  the  sectional  method  in  so  far  as  the  actual  require- 
ments are  concerned. 

In  considering  the  second  feature,  the  absence  of  a  joint  or  seam  of 
solder  may  be  proclaimed  as  an  advantage  in  three  instances  of  detail. 
First,  in  eliminating  the  possibilities  of  the  subsequent  discoloration  of  the 
solder  in  the  joint,  when  subjected  to  the  action  of  the  secretions.  Second, 
in  the  construction  of  a  platinum  crown  which  is  to  serve  as  an  abutment 
for  porcelain  bridgework.  Third,  in  the  construction  of  a  gold  crown  for 
the  bicuspids  where  a  porcelain  facing  is  to  be  subsequently  in- 
serted. 

In  the  first  instance,  if  the  edges  to  be  united  are  closely  fitted  and 
approximated,  the  quantity  of  solder  in  the  joint  is  so  infinitesimal  that 
if  a  high  grade  of  similar  color  be  used,  and  the  crown  then  well  finished 
and  polished,  no  opportunity  will  be  offered  for  any  subsequent  discolo- 
ration ;  hence,  no  special  advantage  is  apparent. 

In  the  second  instance  the  same  advantage  may  be  readily  obtained 
by  permanently  overlapping  the  edges  of  the  band  in  making  the  joint, 
and  closely  approximating  the  edges  of  cusp  and  band,  and  then  using 
platinum  solder  in  their  union.  This  will  preclude  the  re-fusing  or  un- 
soldering of  the  parts  in  the  furnace  during  the  process  of  fusing  the 
porcelain ;  and  the  additional  thickness  of  platinum  which  may  be  used 
when  the  sectional  method  is  employed  adds  materially  to  the  necessary 
strength  which  such  a  crown  must  possess  in  that  particular  portion  of  it 
zvhich  surrounds  the  root. 

In  the  third  instance  the  advantage  is  perhaps  least  imaginary,  but  if 
the  joints  of  the  sectional  crown  intended  for  such  a  purpose  are  made  as 
has  been  indicated,  the  subsequent  attachment  of  the  facing  with  a  lower 
grade  of  solder  may  be  done  without  danger  of  re-fusing  them.  This  may 
be  also  further  prevented,  if  any  doubt  exists,  by  previously  coating  the 
solder  in  such  joints  with  a  solution  of  whiting  in  water  or  alcohol  before 
attaching  the  facing. 

The  features  of  this  style  of  construction  which 

Di$adi;)(inta9C$.         are  of  a  more  or  less  pronounced  disadvantage,  in  a 
general  way,  lie  in  a  consideration  of  the  essentials  of 
time,  strength  and  accuracy  of  adaptation. 


I05 

The    detail    being    more    circuitous,    a    greater 

Z\Mtt  length  of  time  is  necessarily  consumed  in  the  process. 

If  better  results  by  this  method  than  by  any  other 

were  possible,  this  should  not  necessarily  be  a  consideration,  but  it  becomes 

a  matter  of  much  concern  when  equally  good  results  may  be  obtained  by 

another  method  in  less  time. 

The  fact  that  a  much  thinner  gauge  of  metal 
Strcnglb.  must  be  used  to  begin  with,  and  that  it  must  then  be 

subjected  to  considerable  stretching,  is  conspicuously 
a  disadvantage,  because  of  the  extreme  thinness  and  consequent  weak- 
ness of  the  finished  crown.  While  sufficient  re-enforcement  of  the  occlusal 
portion  may  be  afterward  made,  the  band,  where  equal  and  uniform 
strength  is  usually  required,  must  remain  inherently  weak,  or  be  stiffened 
at  the  expense  either  of  the  root  or  of  the  contour. 

As  a  degree  of  accuracy  must  be  insured  in  the 
Jldaptation.  process,  the  adaptation  to  the  root  of  a  primary  or 

temporary  band  is  necessary.  This,  how^ever,  in  one 
particular  is  a  disadvantage,  because,  irrespective  of  however  accurate  it 
may  be,  each  subsequent  reproduction  of  a  given  form  is  less  accurate  than 
the  original,  unless  they  may  be  stamped  in  indestructible  and  unyielding 
dies,  which  qualities  are  not  possessed  by  fusible  alloys,  such  as  are  used 
for  the  dies  in  this  work. 

Detail  of  ConstrNctiON. 

While  there  are  many  and  varied  methods  of  detail  for  the  construc- 
tion of  seamless  crowns,  but  one  general  line  of  procedure  will  be  found 
to  give  results  which  are  sufficiently  reliable  to  insure  an  approach  to  the 
neces:  ary  degree  of  accuracy. 

This  constitutes  taking  a  measurement  of  the  root,  after  its  prepara- 
tion, and  making  and  fitting  a  primary  band,  the  exact  shape  and  con- 
formation of  which  is  then  subsequently  reproduced  in  the  finished  crown. 

The  primary  band  may  be  made,  preferably,  of 
Primary  Band.  32  gauge  copper,  cut  to  ordinary  width,  the  exact 
length  of  the  measurement,  with  straight  edges,  and 
soldered  as  usual.  Or  a  seamless  band  may  be  made  by  selecting  the 
drawing  punch  over  which  the  circular  measurement  will  fit  most  closely, 
and  then  drawing  a  blank  down  to  this  same  size.  By  then  punching  out 
the  top,  a  seamless  band  results,  which  approximates  the  size  of  the  root 
as  closely  as  the  measurement  fitted  the  punch.  Those  preferring  the  latter 
usually  have  a  selection  of  these  blanks  already  drawn  to  various  sizes, 
which  is  an  economy  of  time. 

When  the  band  has  been  made,  it  should  be  trimmed  and  fitted  to  the 


io6 

root  with  the  same  degree  of  care  and  precision  as  though  it  were  intended 
for  permanent  use.  It  should  then  be  cut  away  upon  the  buccal  and  lingual 
surfaces  until  but  a  narrow  rim  remains,  allowing  the  approximal  surfaces 
to  remain  sufficiently  wide  to  be  closely  adapted  to  the  adjacent  teeth. 
(Fig.  90.)  By  so  shaping  it,  a  perfect  restoration  of  the  contact  points 
may  be  made,  and  increased  opportunity  is  afforded  for  forming,  shaping, 
modifying  or  exaggerating  the  buccal  and  lingual  surfaces  as  may  be 
desired. 

When  the  fitting  and  trimming  has  been  com- 

BltC  and  TmprcsslOlt.    pleted,  the  bite    and    impression    should    be    taken. 

While  this  is  often  done  at  one  and  the  same  time, 

with  wax  or  modeling  compound,  a  separate  bite  in  wax,  and  impression 

in  plaster  is  preferable,  and  safer,  because  of  the  uncertainty  of  replacing 

the  band  in  its  exact  and  proper  position  in  the  former  materials. 

When  these  have  been  secured,  and  the  band  accurately  replaced  in 
position  in  the  impression,  the  model  should  be  obtained,  the  bite  adjusted 


f/cf.90.  Ficj.QL  Fi(j.9Z. 


to  it,  and  both  securely  mounted  upon  the  articulator.  After  separating, 
the  surfaces  of  the  adjacent  and  occluding  teeth  should  be  varnished  and 
the  band  and  space  filled  with  thin,  well-mixed  plaster,  and  the  articulator 
firmly  closed. 

This  portion  of  the  procedure  and  the  subsequent  carving  and  shap- 
ing of  the  plaster  is  almost  identical  with  the  detail  previously  outlined  in 
carving  cusps,  and  all  of  the  necessary  artistic  work  must,  of  course,  be 
done  at  this  stage,  because  the  ]:)ermanent  crown  will  be  a  close  reproduc- 
tion of  this  model. 

The  only  difference  in  the  detail  is  that  the  form  and  alignment  of 
buccal  and  lingual  surfaces  is  obtained  by  shaping  the  plaster,  instead  of 
contouring  the  wider  band,  and  that  it  should  be  done  7vithont  detaching 
the  band  from  the  model,  and  also  that  the  plaster  should  be  left  flush, 
even  and  continuous  with  the  band,  instead  of  being  trimmed  to  expose 
its  edge  as  for  a  swaged  cusp. 


lOT 

When  the  necessary  carving  has  been  completed, 
Preparing  models,     the  model  should  be  detached  from  the  articulator, 
and  trimmed  down  until  only  enough  remains  to  form 
a  base  for  the  crown,  as  indicated  in  Fig.  91. 

This  plaster  base  is  then  trimmed,  so  as  to  be  favorable  for,  and 
facilitate  handling  during  the  process  of  securing  the  die,  and  to  give 


adequate  depth  or  body  to  the  latter.  The  plaster  base  immediately  ad- 
jacent to  the  cervical  portion  of  the  band  should  be  cut  away  sufficiently 
to  expose  the  full  thickness  of  the  edge,  which  thus  stands  out  in  the  die 
and  indicates  the  outline,  after  swaging,  to  which  the  finished  crown 
should  be  trimmed.     (Fig.  92.) 

Various  designs  of  casting  flasks  have  been  de- 
Castlng  TIaskS.        vised  for  the  purpose  of  serving  as  a  matrix  in  se- 
curing the  dies  with  fusible  alloy.     Much  similarity 
of  principle  exists  between  them  all,  and  the  one  which  is  a  part  of  the 


Seamless  Crown  Outfit,  manufactured  by  the  Consolidated  Dental  Manu- 
facturing Company  (Fig.  93),  is  simple  and  conveniently  adequate  for 
such  purposes;  though  those  designed  by  Dr.  W.  H.  Trueman  (Fig. 
94a)  (which  must  be  held  in  a  vise  while  swaging),  and  the  Berry  Dental 
Manufacturing  Company  (Fig.  94b),  will  be  found  to  favorably  meet 
the  requirements. 


io8 

In  securing  the  die,  the  plaster  model  containing 

DICJ.  the   crown   should  be   thoroughly   dried  to   prevent 

any  bubbling  of  the  metal,  dusted  with  lycopodium, 

and  then  placed  on  a  smooth  level  surface  of  steel  or  mouldine,  so  as  to 

rest  firmly  and  sustain  a  perpendicular  position  and  the   casting   flask 

placed  over  and  around  it. 

A  piece  of  thin  cardboard  should  be  adjusted  to  the  grooves  in  each 
side  of  the  flask,  and  trimmed  to  foUo-iv  the  outline  of  the  model  (Fig.  95). 
These  are  intended  to  facilitate  the  subsequent  separation  of  the  die  into 
two  lateral  halves,  but  should  not  come  in  contact  with  the  model  at  any 
point. 

The  flask  should  then  be  filled  with  fusible  alloy,  poured  when  in  the 


FJ^.95 


plastic  state,  in  order  to  insure  a  smooth,  well-defined  casting,  and  to 
facilitate  the  separation  of  the  crown  from  it. 

Another  method  is  to  first  fill  the  flask  with  tlie  molten  alloy,  after 
adjusting  the  cardboard,  and  then  firmly  force  the  model  into  the  center 
of  the  metal  just  before  the  process  of  crystallization  takes  place,  holding 
it  in  position  until  it  has  thoroughly  hardened.  If  done  just  at  the  right 
moment,  this  method  is  productive  of  good  results,  but  the  procedure  is 
somewhat  more  uncertain  than  the  former. 

After  chilling  the  metal  with  cold  water,  it  should  be  removed  from 
the  flask  and  the  cardboard  detached.  By  inserting  a  chisel  into  one  of 
the  grooves  thus  formed,  and  striking  it  a  moderate  blow,  the  die  may  be 
easily  separated  into  two  parts.  (Fig.  96.)  The  model  is  now  removed 
from  the  die,  and  the  parts  may  be  readjusted  to  proper  relation,  and  re- 
placed in  the  flask,  which  possesses  a  guiding  notch  to  insure  proper  read- 


log 

justment,  and  which  holds  them  securely  together  during  the  process  of 
swaging  the  crown. 

The  seamless  blank,  or  cartridge,  which  is  to  be 
fcririna  Blanks.      conformed  to  the  desired   outline  of  the  permanent 

crown,  by  swaging,  should  now  be  formed. 
For  this  purposes  all  of  the  "Systems"  or  "Outfits"  contain  or  include 


a  steel  plate  with  perforations,  the  diameters  of  which  range  consecutivei3' 
from  the  h.  gest  to  the  smallest  useful  sizes,  with  a  set  of  steel  punches 
correspondingly  graded. 

A  disk  of  22  karat  gold,  not  thicker  than  30,  or  thinner  than  32  gauge, 
should  be  procured.  These  are  prepared  by  the  supply  houses  in  various 
sizes.    The  two  sizes  most  convenient  for  molars  and  bicuspids  are  illus- 


/yy.97. 


trated  in  Fig.  97  and  may  be  symmetrically  cut  from  plate  by  using  an 
accompanying  copper  disk,  or  the  end  of  a  drawing  punch  as  a  guide. 
These  disks  are  formed  into  the  blank  by  driving  them  through  the 
holes  in  the  plate  with  the  drawing  punches,  beginning  with  the  largest 
size  and  passing  through  each  consecutive  perforation  until  the  blank  is 
reduced  to  a  size  which  will  admit  of  its  being  gently  forced  into  the  die. 


# 


no 

If  a  seamless  primary  band  has  been  used,  the  size  of  the  drawing 
punch  last  used  in  its  formation  will,  of  course,  indicate  the  size  of  the 
blank  required  for  the  crown,  and  the  size  or  number  should  be  desig- 
nated or  remembered. 

The  gold  should  be  annealed  often  during  the  process  to  prevent 
tearing,  and  slightly  oiling  the  end  of  the  punches  and  the  interior  of  the 
perforations  will  be  found  advantageous  in  facilitating  the  drawing  and 
preventing  the  blank  from  sticking  to  the  former. 

The  drawing  press  designed  for  this  purpose  by  Dr.  W.  M.  Sharp 
may  be  found  useful.  It  can  be  securely  fastened  to  the  bench  and  the 
blank  is  formed  by  means  of  a  screwpress  instead  of  driving,  which  re- 


rj<jf.9d. 


suits  in  its  being  drawn  more  evenly  and  uniformly  than  by  intermittent 
blows. 

When  the  blank  has  been  formed  to  the  desired 

Swagittfl*  size,  it  should  be  cleaned  in  the  acid  bath,  and  then 

annealed.     The  surface  of  the  die*  should  be  oiled 

and  the  blank  gently  forced  well  down  into  place  with  a  blunt  piece  of 

soft  wood  of  suitable  size,  and  a  small  hammer. 

Any  excessive  surplus  of  band  may  be  previously  trimmed  away  to 
facilitate  swaging,  but  care  should  be  exercised  not  to  trim  too  much. 

The  interior  of  the  blank  should  be  filled  with  a  substance  which  will 
spread  readily  and  evenly  when  pressure  is  applied,  but  which  may  be 
easily  removed  at  any  time  during  the  process. 

Oiled  birdshot,  cornmeal,  pumice  stone,  small  cubes  of  modeling  com- 
pound, base-plate  gutta  percha  cut  into  small  pieces,  pledgets  of  moistened 
cotton,  or  cotton  previously  saturated  with  melted  wax,  stiff  putty  mixed 
with  soapstone  and  tin  foil  rolled  into  small  globules  are  used. 

The  swaging  is  then  accomplished  by  driving  a  blunt  piece  of  wood, 
or  the  end  of  a  drawing  punch  a  few  sizes  smaller,  into  the  blank  thus 


Ill 

filled.  If  necessary,  the  gold  may  be  removed  and  annealed  several  times, 
though  once  after  starting  and  during  the  process  is  all  that  is  usually 
required. 

When  the  swaging  has  been  completed,  the  sur- 

Hdaptins  plus  should  be  trimmed  away  to  closely  follow  the 

and  RC-cnforcing,      cervical  outline  indicated  in  the  band,  and  the  crown 

slightly  heated  and  subjected  to  the  acid  bath,  when 

it  may  be  re-enforced  with  a  high  karat  of  solder  or  a  lower  karat  of 

plate  gold,  rolled  thin,  and  finished. 

If  the  finished  crown  should  be  too  large,  it  may  be  reduced  with 
pliers  before  re-enforcing,  or  if  viiich  too  large  as  a  result  of  compressing 
the  walls  of  the  die  during  the  process  of  swaging,  it  may  be  first  cut  in 
two  lateral  halves,  left  in  the  die,  and  another  crown  swaged  inside  of  it ;  or 
if  too  small,  which  is  rarely  the  case,  it  may  be  stretched  sufficiently  with 
pliers.  Where  some  expanding  or  compressing  of  the  bulbous  portion  may 
be  indicated  in  order  to  improve  the  contact  with  adjacent  teeth, the  rotary 
point  contouring  pliers  designed  by  Dr.  C.  W.  Miller  will  be  found  useful 
(Fig.  98). 

While  many  of  the  various  "systems"  provide  means  for  securing 
the  model  from  a  selection  of  typical  forms  of  approximate  sizes,  from 
which  the  dies  are  made;  and  for  securing  the  outline  of  the  occlusal  sur- 
face by  subsequently  swaging  in  a  typical  die-plate,  or  other  similar  man- 
ner, the  possible  results  obtained  from  such  methods  do  not  merit  con- 
sideration because  of  being  but  little,  if  any,  more  accurate  than  ordinary 
ready-made  crowns. 


Kcper$c  Procc$$. 

In  the  preceding  process  it  will  be  noted  that  in  the  detail  of  swag- 
ing, the  blank  is  conformed  to  the  outline  of  a  mould  or  die  of  the  orig- 
inal model,  by  expanding  or  stretching  it.  This  is  termed  the  '^inside- 
out"  method,  and,  while  it  is  perhaps  most  generally  used,  the  extreme 
thinness  of  the  finished  crown,  augmented  by  the  necessity  of  begin- 
ning with  so  thin  a  gauge,  very  consistently  occasions  the  objectionable 
features  already  intimated  in  this  connection. 

As  a  means  of  overcoming  such  objections,  and  obtaining  increased 
thickness  and  strength,  the  rei'crsc  or  "ontside-in"  process  of  swaging 
has  been  devised. 

In  this  method  the  blank  is  conformed  by  being-  compressed  over  a 
metal  reproduction  of  the  original  model,  instead  of  being  expanded  to 
meet  the  walls- of.  a  mould. 0/  it. 


112 

While  the  process  of  swaging  is  perhaps  more 

JIdoantages.  difficult  to  accomplish,  the  results  are  advantageous 

in  being  productive  of  a  heavier  and  more  uniform 

thickness  of  gold  in  the  finished  crown,  and  of  greatly  diminishing,  if 

not  entirely  overcoming,  the  probability  of  tearing  it. 

The  result  obtained  by  swaging  the  gold  over 
Disadvantages.  the  outside  dimensions  of  a  metal  reproduction  of 
the  original  and  desired  form^  would  seem  to  be  ob- 
jectionable in  that  the  crown  so  conformed  must  be  somewhat  larger 
than  the  model.  This,  together  with  the  tendency  of  the  gold  to  over- 
lap and  knuckle  here  and  there,  during  the  swaging,  are  logical  disad- 
vantages, unless  means  are  observed  for  overcoming  them. 

While  the  overlapping  and  knuckling  may  be  easily  avoided  by  care- 
ful manipulation  of  the  gold  during  the  process,  the  difference  in  size 
occasioned  by  the  thickness  of  gold  can  be  overcome  only  by  using  force 


Fiq  99  ^ 


enough  in  swaging  to  so  compress  the  die  by  the  impact  as  to  compen- 
sate for  this  thickness,  or,  by  removing  the  primary  band  just  previous 
to  reproducing  the  metal  model. 

In  view  of  the  characteristics  of  the  lower  melting  fusible  alloys 
which  are  necessarily  used,  and  of  the  thinness  of  the  gold  after  being 
drawn  down  to  the  required  size  blank,  it  is  possible  that  fairly  accurate 
results  may  be  obtained  by  depending  upon  the  compression  of  the  metal 
model  from  the  force  and  impact  of  swaging;  yet  as  this  is  more  or 
less  uncertain,  the  removal  of  the  band  is  the  prefcra1)lc  procedure  and 
will  afford  the  most  positive  and  accurate  results. 

As  the  variation  between  this  and  the  preceding 
Procedure.  method  pertains  only  to  the  manner  of  securing  the 

dies,  and  to  the  process  of  swaging,  the  procedure 
up  to  the  point  of  obtaining  the  model  is  identical  with  that  already  out- 
lined. 


113 


the    same    manner 
the    dies,  excepting 


When  the  crown  has  been  removed  from  the  artic 
Original  model.        ulator,  and  its  plaster  base  trimmed  to  the  required 
form  as   previously   indicated  in  Fig.  92,  it  should 
ihen  be  reproduced  in  fusible  alloy,  instead  of  obtaining  metal  dies  of 
't  in  the  form  of  a  mould. 

If  the  band  is  to  be  removed  from  the  model,  the  plaster  base  should 
be  trimmed  away  sufficiently  deep  so  as  to  leave  a  distinct  cervical  out- 
line to  guide  in  trimming  the  crown  after  swaging.  The  removal  of  the 
band  may  be  easily  accomplished  b}  cutting  through  it  at  the 
narrowest  and  most  convenient  point,  with  a  fine  saw-  or  file,  after 
which  the  entire  plaster  outline  should  be  nicely  smoothed  down,  and 
then  varnished. 

The   mould    is   obtained    in 
mould.  formerly    pursued    in    securing 

that  it  is  made  of  plaster  in- 
stead of  metal.  The  varnished  model  should  be 
adjusted  to  the  casting  flask,  or  similar  device, 
with  pieces  of  cardboard  in  situ.  Fig.  95,  and  thin 
plaster  then  poured  upon  it.  After  crystallization 
this  may  be  broken  open,  the  model  removed,  and 
the  parts  replaced  and  adjusted  to  the  flask. 

When  the  plaster  has  be- 
Swafling  model.  come  sufficiently  dry,  this 
should  be  filled  with  fusible 
alloy  which  melts  at,  or  below,  the  temperature 
of  boiling  water.  The  metal  model  thus  resulting, 
h'ig.  99,  is  identical  with  the  original  model,  and 
over  this  the  blank  of  gold  is  conformed  by  vari- 
ous processes  of  swaging. 

After  drawing  the  blank  to  a  size  which  will  fit 
Blanks.  snugly    over    the    swaging   model,    or    securing   the 

same  from  the  supply  houses  in  ready-made  form,  it 
should  be  first  thoroughly  annealed,  as  any  subsequent  annealing  is  pre- 
vented after  the  swaging  has  been  started,  because  of  the  necessity  for 
tlie  destruction  of  the  swaging  model,  by  melting  it,  to  admit  of  the  re- 
moval of  the  blank. 

In  conforming  the  blank  to  the  outlines  of  the 
Swaging.  swaging  model,  considerable  care  must  be  exercised 

to  prevent  knuckling  and  overlapping  of  gold  by  any 
method  employed.  This  can  only  be  accomplished  by  frequently  remov- 
ing the  crown  and  working  out  such  places  with  a  small  riveting  ham- 
mer, Fig.  100. 


114 

While    several    systems   and   devices  have   been 

methods.  designed  for  the  purpose  of  swaging  crowns  by  this 

process,  the  cylinder  and  plunger  are  the  essential 

features  of  the  most  useful  ones,  and  even  hydraulic  pressure  may  be  very 

serviceably  employed. 

Ash's  crown  swaging  device  can  be  made  to  answer  the  purpose  by 
boring  out  the  end  of  the  plunger  until  it  presents  the  form  of  a  cone 
equal  in  depth  to  that  of  the  average  crown,  and  a  similar  apparatus  es- 
pecially designed  to  meet  such  requirements  constitutes  a  portion  of  the 
seamless  crown  outfit  manufactured  by  Mr.  J.  W.  Place,  of  New  York 
City.  The  cone  shape  plunger  is  necessary  in  order  to  distribute  the  im- 
pact evenly  over  the  entire  surface  of  the  crown. 


Fiq  102 


In  the  use  of  such  devices  the  blank  should  first  be  fitted  over  the 
swaging  model  and  gradually  worked  down  to  place  with  the  riveting 
hammer.  .  This  should  be  placed  in  the  center  of  the  cylinder  and  oiled 
bird-shot  or,  preferably,  stifle  putty  freely  mixed  with  lycopodium  or  soap- 
stone,  then  packed  closely  around  and  over  it  until  entirely  submerged. 
The  plunger  should  now  be  inserted  and  gradually  driven  to  place,  re- 
moving the  crown  frequently  and  working  out  the  overlaps,  until  the 
swaging  is  completed. 

The  apparatus  designed  by  Dr.  W.  P.  Scott,  of 
Scott's  method.        Chicago,  v/hich  consists  of  an  inverted  cone  shaped 
cylinder,  and  straight  flat-surface  plunger,  with  other 
necessary  accoutrements,  is  among  the  most  complete,  simple  and  mod- 
ern inventions  for  this  work,  though  it  is  similar  to,  and  used  much  in 
same  manner  as  the  Berry  and  Adam  son  outfits. 

In  the  use  of  this  system  the  blank  is  fitted  to  the  swaging  model 
as  indicated,  and  the  occlusal  surface  first  swaged  by  driving  the  same 
into  a  surface  of  lead.  After  this  portion  of  the  crown  is  adequately 
swaged,  it  is  then  placed  in  a  matrix  afiforded  between  the  two  surfaces 
of  lead    which  are  formed  in  a  mould  accompanying  the  outfit,  and  the 


115 

whole  then  dropped  into  the  cyHnder.  The  base  and  top  of  the  lailci 
are  adjusted,  and  the  plunger  inserted,  (Fig.  loi,)  which  upon  being 
driven  deeper  into  the  cylinder  so  compresses  the  lead  matrix,  and  the 
gold  blank,  as  to  closely  conform  it  to  the  outlines  of  the  swaging  model, 
with  a  minimum  tendency  to  tear  or  overlap,  and  with  a  maximum  and 
uniform  increase  in  the  thickness  of  the  gold.  The  lead  matrix  before 
and  after  swaging,  together  with  the  crown  in  position  in  the  latter,  are 
illustrated  in  Fig.  102. 

When  the  swaging  has  been  adequately  accom- 
TinisMng.  plished  by  the  method  selected,  very  little  finishing 

is  usually  required.  The  crown  should  be  polished 
before  detaching  it  from  the  metal  model,  after  which  the  latter  should 
be  melted  by  placing  in  boiling  zvater,  and  any  adhering  or  remaining 
particles  removed  by  the  acid  bath.  The  surplus  gold  at  the  cervical  por- 
tion should  then  be  carefully  trimmed  away  to  follow  the  outline  indi- 
cated, when  the  necessary  reinforcement  and  final  polishing  may  be 
given. 


Ficj.  1 04-. 
Fi<j.l03, 

Jfpplication  to  Separatca  IDolar  Roots. 

The  presentation  of  cases  where  molar  roots  have  become  separated 
at  the  bifurcation  as  the  result  of  extensive  disintegration  of  the  crown, 
and  with  each  individual  root  remaining  firm  in  its  attachment,  is  not  an 
infrequent  or  unusual  occurrence. 

In  such  instances  the  application  of  a  crown  will  not  only  often 
restore  the  roots  to  the  former  usefulness  and  supply  the  serviceability  of 
the  original  tooth  for  many  years,  but  will  also  frequently  preclude  the 
impaired  occlusion  of  the  adjacent  teeth  which  their  natural  gravitation 
or  tipping,  as  the  result  of  the  loss  of  such  roots,  would  occasion. 

This  latter  phase  places  a  degree  of  importance  upon  the  permanent 
letention  of  these  roots,  which,  particularly  in  early  life,  and  especially  on 
first  molars,  makes  such  a  procedure  of  inestimable  value,  and  causes  it  to 
be  almost  universally  indicated  wherever  such  a  condition  is  found  in 
otherwise  unbroken  or  well-filled  arches,  with  the  roots  remaining  rea- 
sonably firm. 


ii6 

In  the  treatment  of  these  cases   the   individual 

Procedure.  roots  should  be  carefully  prepared  by  observing  the 

therapeutic  and  mechanical  requirements,   and   each 

then  built  up  separately  with  amalgam  (anchored  with  a  post,  or  by  other 

mechanical  retention)  until  they  afford  favorable  shape  for  the  permanent 

attachment  of  a  band.      (Fig.  103.) 

Separate  bands  should   be  fitted  to  each,   their 
Bands.  occlusal  ends   trimmed   to  allow   for  the   cusp,   and 

contoured   to   approximate    each   other,   and   restore 
contact  with  adjacent  teeth. 


The  usual  bite  in  wax  and  impression  in  plaster  should  be  secured, 
and  the  case  finally  mounted  upon  the  articulator.  After  separating,  and 
detaching  the  bands  from  the  model  in  such  manner  as  to  preserve  their 
outline  and  admit  of  accurate  replacement,  they  should  be  readjusted  to 
the  model  and  united  securely  together  with  hard  wax ;  then  they  may 
be  removed  and  the  cervical  one-half  imbedded  in  investment  material. 
Their  relation  may  now  be  permanently  sustained  by  filling  in  between 


Fiq.  106. 


them  With  22  karat  solder,  which  union,  involving  the  occlusal  ends  only, 
will  leave  a  free,  clean  interproximal  space.      (Fig.   104.) 

The  united  bands  may  now  be  replaced  upon  the 

€U$P$.  model  and  the  cusps  formed  in  the  usual  manner,  as 

though   for  the  single  band  of  an  ordinary  crown. 

In  attaching  them,  however,  care  must  be  exercised  to  prevent  re-fusing 

the  solder  with  which  the  bands  were  previously  united,  and  thus  chang- 


117 

ing  or  destroying  the  relation  between  them.  The  use  of  a  lower  grade 
solder  will  ordinarily  preclude  this,  but  to  further  facilitate  it  the  cusps 
should  be  filled  with  solder  after  obtaining  their  proper  adaptation,  and 
previous  to  attaching  them  to  the  bands.  Very  little  danger  will  then 
exist,  and  a)iy  may  be  entirely  overcome  by  the  use  of  a  solution  of 
whiting  and  alcohol,  which  precaution  it  is  well  to  observe. 

Jfpplicdtion  to  TndiPidual  Roots. 

Where  but  a  single  root  remains  or  possesses  sufficient  strength,  and 
particularly  in  the  lower  jaw,  it  may  often  be  retained  and  made  service- 
able for  a  number  of  years  by  the  application  of  a  crown.  Also,  in 
instances  where  such  a  root  may  be  vmusually  strong,  and  the  space 
formerly  occupied  by  the  normal  tooth  has  become  lessened  or  partially 
closed  as  a  result  of  the  loss  of  the  other  root  and  the  gravitation  of  the 
adjacent  teeth,  it  is  often  practical  to  extend  the  occlusal  portion  of  the 
crown  until  it  rests  against  the  adjacent  tooth,  and  thus  affords  a  con- 
tinuous masticating  surface.  (Fig.  105.)  The  contact  point  between 
such  a  crown  and  the  natural  tooth,  however,  should  be  only  sufficient  to 
prevent  tipping  of  the  root  from  the  stress  of  mastication,  and  for  prophy- 
lactic reasons  should  rest  close  to  the  occlusal  surface  and  be  smooth 
and  well  rounded. 

Cantilever  Bridges. 

A  small  intervening  space  between  two  artificial  crowns  may  be 
bridged  over  until  an  unbroken  masticating  surface  presents,  by  applying 
these  same  principles,  as  was  originally  suggested  by  Dr.  J.  N.  Farrar. 
(Fig.  106.)  Such  a  procedure  would  be  most  practical,  however,  in  cases 
where  a  very  small  space  existed,  as  one  sufficiently  large  to  accommodate 
a  dummy  could  usually  be  best  filled  by  constructing  an  assembled  bridge. 

Jlpplicatiott  of  Jfmal0am. 

Amalgam  is  sometimes  employed  in  the  restoration  of  badly  broken 
down  molar  roots  by  crowning,  and,  while  good  results  in  the  line  of  expe- 
ditious operations  combined  with  a  moderate  degree  of  preservation  and 
permanency  are  probably  possible,  any  method  possessing  only  the  advan- 
tages of  time  and  cost  of  production,  and  requiring  less  skill  and  effort 
than  a  manifestly  better  and  more  artistic  one,  should  very  naturally 
occupy  the  limited  sphere  of  application  and  usefulness  accorded  to  this. 

In  conditions  and  environments,  however,  which  seem  to  indicate  the 
application  of  such  methods,  it  is  possible  to  obtain  fairly  good  results  in 
the  restoration  of  the  crowns  of  second  and  third  molars,  where  the  occlu- 
sion is  very  close,  by  either  of  the  following  procedures : 


ii8 

Where  a  permanent  band  may  seem  indicated  as 

Klltb  Band.  a  means  of  supporting  the  remaining  walls  of  the 

root,  and  to  aid  in  the  retention  of  the  amalgam,  it 
should  be  made  of  gold,  carefully  fitted  and  adapted,  and  then  polished 
and  cemented  to  place. 

Provisions  should  then  be  made  for  securely  retaining  the  amalgam. 
This  may  be  accomplished  either  by  means  of  a  post,  cemented  into  one 
of  the  canals,  or  by  cutting  a  mechanically  retaining  cavity  if  sufficient 
tooth  structure  remains. 

Very  plastic  amalgam  should  then  be  packed  thoroughly  to  place, 
and  built  up  to  the  desired  cusp  formation,  until  a  favorable  occlusion  is 
obtained. 

After  crystallization,  and  preferably  at  a  subsequent  sitting,  the 
amalgam  cusps  should  be  well  finished  and  polished ;  and,  while  the  gold 
band  will  have  assumed  the  same  color  by  the  superficial  absorption  of 
mercury,  its  original  color  may  be  brought  back  by  polishing,  if  desired. 

If  a  permanent  band  is  not  desired,  or  seemingly 
UlitbOUt  Band.  unnecessary,  the  entire  crown  may  be  made  with  the 
amalgam.  In  this  procedure  a  temporary  band  of 
thin  German  silver,  32  to  34  gauge,  should  be  made  and  adapted  to  the 
root,  as  indicated.  This  is  used  only  as  a  matrix  for  aid  in  adapting  and 
contouring  the  amalgam,  and  may  be  easily  removed  from  the  latter,  after 
its  crystallization,  by  cutting,  after  which  the  amalgam  crown  may  be 
finished  and  polished.  The  easy  removal  of  the  band  may  be  further 
facilitated  by  coating  its  inner  surface  with  vaseline  or  oil  before  inserting 
the  amalgam,  which  will  prevent  superficial  amalgamation  with  it. 

Where  extensive  destruction  mav  preclude  sufficiently  adequate  reten- 
tion for  the  amalgam,  it  may  be  fy'st  tightly  packed  to  the  surface  of  the 
tooth  and  matrix,  and  around  the  projecting  end  of  a  aowel  temporarily 
adjusted  to  the  canal  if  the  use  of  the  same  seems  indicated, 
without  any  provisions  for  its  retention.  After  crystallization 
both  may  be  removed,  the  band  separated,  and  the  crown  then 
finished  and  polished,  and  finally  mounted  with  cement,  after  serrating  or 
roughening  the  surfaces  of  crown  and  root.  Such  operations,  however, 
are  of  douljtful  permanency  as  compared  with  those  wherein  a  permanent 
band  is  employed. 

Jlpplicatiott  to  the  interior  Ceetb. 

While  it  is  difficult  to  conceive  of  a  practice  more  flagrantly  inartistic 
than  the  ap])lication  of  gold  crowns  to  anterior  teeth  or  roots,  as  has  been 
previously  observed,  they  are,  nevertheless,  occasionally  employed. 


119 

In  view  of  the  opportunities  for  more  artistic  endeavors,  and  the  in- 
creasing appreciation  of  and  demand  for  the  same,  this  class  of  gold  crown 
is  now  the  exceptional  expedient  rather  than  the  common  practice, 
and  would  doubtless  soon  become  entirely  obsolete  were  it  not  for  a 
limited  class  of  cases  in  which  the  requirements  and  environments  seem  to 
justify  such  a  procedure. 

Their  application  in  any  event,  including  even  these  exceptional  con- 
ditions, should  be  made  with  an  honesty  of  purpose,  and  a  sense  of  profes- 
sional duty,  paramount  to  a  mere  catering  to  the  perverted,  unrefined 
vanity  of  the  vainglorious. 

The  class  of  cases  in  which  their  application  is 

Tndications.  practicable  and  warrantable  is  confined  to  the  mouths 

of  men  past  middle  age,  where  they  are  partially  or 
entirely  hidden  by  the  beard.  In  such  instances  the  use  of  gold  crowns 
may  be  indicated  in  two  general  classes  of  cases : 

First,  where,  from  a  more  or  less  powerful  masticating  action,  and  by 


f/(j[J07. 


years  of  constant  and  continued  attrition,  the  remaining  teeth  have  become 
so  worn  down  as  to  require  restoration  with  an  absolutely  indestructible 
material.  Second,  in  crowning  the  cuspid  teeth,  when  they  are  to  serve 
as  abutments  for  bridgework,  and  where  it  is  desirable,  and  perhaps  neces- 
sary from  a  mechanical  standpoint,  to  allow  as  much  as  possible  of  the 
natural  crown  to  remain  in  order  to  secure  the  additional  strength  thus 
imparted  to  the  attachment  between  crown  and  root ;  and  where  the  prac- 
tical invisibility  of  the  work  may  not  require  any  special  effort  toward 
securing  the  more  artistic  effects  afforded  by  other  means. 

The  first  class  of  cases  are  not  uncommon  or  infrequent,  and  usually 
present  a  more  or  less  perplexing  problem.  If  an  adequate  number  of 
the  posterior  teeth  remain,  and  occlude  with  teeth  in  the  opposing  jaw,  a 
more  artistic  result  may  often  be  obtained  by  crowning  the  posterior 
teeth  in  such  a  manner  as  to  opoi  the  bite  sufficiently  to  accommodate 
crowns  having  porcelain  facings  on   the  anterior  teeth,   with  reasonable 


120 

assurances  of  permanency  and  usefulness.  But  in  the  event  of  the  loss  or 
absence  of  properly  occluding  posterior  teeth,  all,  or  the  greater  portion, 
of  the  work  of  mastication  may  be  thrown  upon  the  remaining  anterior 
teeth,  and  thus  preclude  the  use  of  porcelain  and  occasion  the  necessity 
for  gold,  unless  the  posterior  teeth  be  first  supplied  by  artificial  dentures. 

Fig.  107  illustrates  a  case  where  the  bite  was  opened  by  placing 
crowns  upon  the  posterior  teeth,  with  cusps  sufficiently  thick  to  withstand 
the  work  of  mastication,  and  which  thus  admitted  the  application  of  porce- 
lain-faced crowns  to  the  anterior  teeth.  Fig.  108  illustrates  a  case  where 
the  absence  of  the  posterior  teeth  indicated  the  use  of  gold  on  the  remain- 
ing anterior  teeth,  and  where  the  crowns  were  further  fortified  against 
the  stress  of  mastication  by  tipping  each  with  26  gauge  clasp-metal.    The 


use  of  the  clasp-metal  is  especially  indicated  where  both  upper  and  lower 
teeth  are  crowned  and  the  crowns  occlude  with  one  another. 

In    the    application    of    these    crowns,    several 
Procedure.  methods   are   employed.     The   recjuirements   of   root 

preparation,  as  have  been  outlined  in  general,  include 
securing  the  greatest  diameter  at  the  cervix  by  reducing  the  coronal  pro- 
portions, and  further  sacrificing  the  approximal,  labial,  lingual  and  incisal 
surfaces  until  the  remaining  structure  will  admit  of  properly  shaping  and 
contouring  the  crown,  when  the  measurement  should  be  taken  as  hereto- 
fore indicated.  A  band  of  28  or  29  gauge,  22  karat  gold  should  then  be 
cut  the  exact  length  of  the  straightened  measurement  wire,  and  somewhat 
zcidcr  than  the  required  length  of  the  crown. 

As  the  correct  adaptation  can  be  most  accurately 

Adaptation  to  tbe      oljtained  by  fitting  directly  upon  the  root,   and  but 

moutb.  little  time  is  thus  consumed,  the  use  of  models   is 

unnecessary. 

The  band  should  be  soldered,  trimmed  to  meet  the  gum  line  evenly 


121 

(Fig.  109,  a.),  and  then  forced  to  place  upon  the  root.  When  the  cer- 
vical adaptation  has  been  completed,  the  lingual  portion  of  the  band 
should  be  cut  away,  following-  the  original  curvature  and  outline  of  the 
tooth.  (Fig.  109,  b.)  The  labial  surface  may  now  be  contoured  with 
the  pliers  until  it  assumes  proper  shape  and  alignment,  and  restores  con- 
tact with  adjacent  teeth,  in  which  the  artistic  results  possible  are,  of 
ccrtirse,  in  proportion  to  the  degree  of  skill  displayed. 

The  incisal  end  should  now  be,  trimmed  to  the  proper  length  and 
shape,  with  an  allowance  for  the  thickness  of  the  lingual  plate  to  be  sub- 
sequently attached,  and  of  the  clasp-metal  also,  should  its  use  be  desirable 
or  necessary. 

A  piece  of  gold,  somewhat  larger  than  necessary,  28  to  30  gauge,  22 
karat,  should  be  adapted  to  the  lingual  portion  of  the  band,  held  in 
contact  with  pliers  or  wire,  and  soldered  from  the  inside.     (Fig.  109,  c.) 


Adequate  re-enforcement  of  the  incisal  end  should  be  obtained  by 
filling  in  sufficiently  with  solder,  or  by  attaching  a  piece  of  clasp-metal, 
previously  cut  to  the  exact  size  and  shape,  along  the  edge. 

The  surplus  should  be  cut  away,  and  the  crown  subjected  to  the  acid 
bath ;  then  finished  and  polished. 

When  it  may  become  necessary,  or  seem  desir- 

TldaptatiOlt  able,  to  construct  the  crown  upon  models,  thus  con- 

tO  models,  fining  the  work  to  the  laboratory,  a  narroiv  primary 

band  of  copper  or  German  silver,  32  gauge,  should 

be  fitted  to  the  root,  and  an  impression,  including  the  adjacent  teeth,  then 

taken  in  plaster. 

When  this  has  been  secured,  the  band  should  be  adjusted  accurately 
to  place,  and  the  model  obtained  with  fusible  alloy,  which  is  preferable  to 
plaster,  being  more  indestructible. 

With  a  sharp  chisel  or  bur  the  outside  surface  of  the  band  on  the 
model  should  be  first  freely  exposed,  when  it  may  be  cut  in  two  and  de- 
tached. This  will  leave  the  adjacent  teeth  and  the  correct  cervical  outline 
of  the  root  definitely  exposed  in  the  model,  and  the  crown  can  then  be 
constructed  upon  it  in  the  manner  indicated,  with  reasonable  accuracy. 


122 

Those   who  may   experience   some   difficulty   in 

Carping  and  Swaging,    shaping  and  contouring  the  labial  surface  with  pliers 

in  an  artistic  manner,  may  be  able  to  obtain  better 

results  by  carving  and  swaging  both  labial  and  lingual  surfaces,  though 

this  method  seems  unnecessarily  circuitous. 

To  accomplish  this  the  primary  band  should  be  fitted,  the  impression 
taken,  and  a  model  secured  in  plaster.  The  band  should  be  carefully 
detached  from  the  model  and  the  latter  varnished.  With  the  band  again 
adjusted  to  position,  the  intended  crown  may  be  formed  with  plaster, 
which,  after  hardening,  may  be  carved  to  the  desired  form.  By  the  use  of 
mouldine  separate  dies  may  now  be  secured  of  the  labial  and  lingual  sur- 
faces, with  the  line  of  junction  at  the  center  of  the  approximal  and  incisal 
surfaces.     (Fig.  no,  a.) 

Each  surface  should  be  swaged  separately ;  the  surplus  trimmed 
away ;  the  edges  passed  over  a  flat  smooth  file  until  they  approximate 


a 


Fiq.llO. 


FiqJlL 


evenly  (Fig.  no,  b.),  and  the  two  finally  soldered,  with  sufficient  incisal 
re-enforcement. 

In  this  procedure  the  degree  of  accuracy  obtained  in  the  finished 
crown  will  depend  much  upon  first  drawing  or  designatmg  a  definite  line 
between  the  two  lateral  halves  of  the  plaster  crown ;  then  securing  an 
imprint  of  each  surface  in  the  mouldine,  having  a  well  defined  edge  evenly 
approximating  this  line,  and  finally  trimming  away  the  surplus  gold, 
after  swaging,  with  care  and  precision  before  uniting  the  two  with  solder. 

The  accuracy  and  indestructibility  of  the  metal  model,  however,  sup- 
plemented by  the  definite  reproduction  of  the  diameter  and  cervical  out- 
line of  the  root,  which  is  afforded  by  the  primary  band,  aids  materially  in 
securing  the  desired  result. 

The  various  die-plate  systems  supplying  a  se- 
Die-Plate  IHctbedS.  lection  of  dies  of  the  labial  and  lingual  surfaces  may 
often  be  employed  to  good  advantage,  with  perhaps 
increased  artistic  effect,  and  a  reasonable  degree  of  accuracy,  though  they 
give  a  more  typical  reproduction  of  tooth-form  than  is  usually  necessary 
or  required,  except  possibly  for  the  cuspid  teeth,  as  considered  in  the 
second  class  of  indications. 


123 


The  dies  for  this  purpose  contained  in  the  Lowry 
Cowry  and  and  ]\Iillett  systems  inckide  only  the  labial  surfaces. 

milieu  Systems.  and  may  be  used  in  accordance  with  their  application 
as  formerly  outlined.  In  their  use  the  measurement 
Is  taken  and  a  band  cut  the  proper  length  and  width.  The  die  is  selected 
which  approximates  the  individual  requirements  of  the 
case,  and  the  immediate  center  of  the  band  is  then  con- 
formed by  swaging;  after  which  it  is  trimmed,  as  indi- 
cated in  Fig.  Ill,  made  in  circular  form,  and  soldered.  It 
is  now  fitted  and  adapted  to  the  root,  trimmed  to  assume 
the  proper  lingual  curvature,  and  to  admit  of  the  attach- 
ment of  the  lingual  plate,  as  previously  shown  in  Fig.  109. 

The    Hollingsworth    and    Baird 
1)0l1ing$W0rtb  and      systems  include  separate  dies  of  both 
Baird  Systems.        the     labial     and     lingual      surfaces 
mounted  on  a  single  base,  and  may 
be  used  in  similar  manner,  in  accordance  with  their  ap- 
plication, as  previously  outlined. 

When  the  die  which  most  closely  approaches  the 
requirements  for  side,  size  and  form  has  been  selected, 
the  gold  should  be  swaged,  and  both  sides  of  the  crown 
then  trimmed  until  properly  approximated.  They  should 
then  be  wired  together,  fluxed,  and  soldered  from  the  in- 
side. (Fig.  112.)  While  it  may  now  be  possible  to  so  trim  and  shape  the 
cervical  end  as  to  secure  a  fairly  good  adaptation  to  the  root,  a  more  ac- 
curate result  may  be  obtained  by  adapting  a  narrow  band  of  gold  to  the 
root  and  then  fitting  the  crown  ozrr  it,  and  subsequently  attaching  them 
with  solder,  when  the  incisal  end  may  be  adequately  re-enforced  and  the 
crown  finished  and  polished. 

The  application  of  the  seamless  method  to  the 
Seamless  method,  restoration  of  anterior  roots  is  identical  in  detail  to 
the  procedure  previously  indicated  in  the  construction 
of  bicuspid  and  molar  crowns.  As  the  lingual  outline  of  the  adjacent 
teeth,  however,  will  often  serve  as  a  guide,  the  taking  of  a  "bite"  becomes 
necessary  only  when  the  opposing  teeth  may  be  irregular,  or  where  an 
incisal  or  "end  to  end"  occlusion  is  required. 

The  primary  band  should  be  made  and  fitted  in  the  manner  outlined, 
and  the  impression  secured  in  plaster.  When  the  model  has  been  obtained, 
the  crown  should  be  formed  and  carved,  and  the  dies  made  in  accordance 
with,  and  the  swaging  accomplished  by,  the  process  selected. 

Seamless  crowns  are  also  especially  useful  for  bicuspids  where  porce- 
lain facings  are  to  be  attached. 


Fi^J/2. 


124 

In  applying  this  method  to  the  construction  of 
Reproductions.  cuspid  crowns  where  the  entire  natural  crown  re- 
mains, accurate  reproductions  of  the  tooth  may  be 
quite  easily  made.  To  accomplish  this,  the  natural  crown  must  first  be 
trimmed  sufficiently  on  the  approximal  sides  to  admit  of  an  accurate  ad- 
justment of  a  band  to  the  cervix,  and,  if  necessary,  upon  the  incisal,  labial 
and  lingual  surfaces,  to  admit  of  securing  the  proper  length,  alignment 
and  occlusion.  A  narrow  primary  band  should  then  be  fitted  to  the  neck 
of  the  tooth,  and  the  impression  and  subsequently  the  model  secured  in 
plaster.  The  plaster  tooth  should  now  be  cut  from  the  model  in  the  man- 
ner indicated  in  Fig.  91,  and  the  dies  or  swaging  model  secured  as  the 
selection  of  processes  may  require.  When  the  swaging  has  been  com- 
pleted, the  crown  will  be  a  close  reproduction  of  the  tooth  and  will  fit  it 
accurately.  Sufficient  incisal  re-enforcement  to  prevent  wearing  through, 
however,  must  always  be  made,  even  at  the  expense  of  grinding  the  nat- 
ural crown,  if  necessary. 

This  procedure  is  sometimes  employed  without  using  the  primary 
band,  but  is,  of  course,  less  accurate,  as  the  band  indicates  the  proper  rela- 
tion to  the  root  under  and  within  the  free  margin  of  the  gum,  which  other- 
wise can  only  be  approximated  by  trimming  the  model  at  this  point. 

In  those  cases  where  the  natural  crowns  are  so 
Dowels.  badly  worn  or  broken  down  as  to  afford  inadequate 

attachment  for  the  crown,  the  use  of  a  dowel  may 
become  necessary  as  a  means  of  supplementing  the  telescope  attachment. 
and  thus  offering  increased  integrity.  Their  application  may  be  made  by 
first  fitting  them  to  the  canal,  and  then  allowing  a  projecting  end  to  extend 
into  the  crown  as  far  as  its  incisal  edge  will  admit.  After  thus  ascer- 
taining the  proper  length,  the  dowel  should  be  previously  cemented  to 
j'lace  in  the  root,  and  the  crown  subsequently  attached. 

Jlpplication  to  Dcciauous  CectD. 

In  some  fortunately  rare  and  exceptional  instances,  where  the  ex- 
tremely poor  character  of  the  deciduous  teeth  precludes  their  temporary 
preservation  by  other  means,  and  demands  the  employment  of  some  heroic, 
or,  perhaps,  radical  procedure  to  prevent  their  premature  loss,  the  appli- 
cation of  gold  crowns  may  be  indicated  as  the  most  sim])le,  expedient  and 
available  means  of  preserving  them  until  the  time  for  the  eruption  of  their 
permanent  successors. 

In  such  cases  little  or  no  ])reparation  would  of  course  jje  possible,  or 
necessary,  and  good  results  may  often  be  accomplished  by  covering  the 
little  crowns  of  such  teeth  with  caps  made  of  pure  gold. 


125 

In  the  procedure  a  Avire  measurement  of  the  cervical  circumference 
should  be  taken,  and  tlicn  an  impression  in  zca.v,  from  which  a  plaster 
model  may  be  secured,  which  will  afford  sufficient  accuracy  for  the 
purpose. 

Pure  gold  about  34  gauge  should  be  then  cut  the  length  of  the  meas- 
urement, made  in  circular  form  and  soldered,  and  then  fitted  and  shaped  as 
accurately  as  possible  on  the  model. 

It  should  then  be  finally  soldered,  with  but  little  reinforcement,  and 
finished  and  polished. 

The  tooth  should  then  be  thoroughly  disinfected,  and  the  crown 
mounted  with  cement,  and  carefully  burnished  to  a  close  adaptation  with 
the  neck  of  the  tooth. 

By  this  means  this  class  of  teeth  may  be  saved  until  the  proper  time 
for  their  loss  with  the  utmost  expedience,  and  without  unduly  taxing  the 
patients  of  such  tender  years. 

Rcadv-ltldde  forms. 

As  a  woful  acknowledgment  and  conclusive  evidence  of  the  lack  of 
skill  possessed  by  some,  and  of  the  ever-ready  willingness  of  the  supply- 
houses  and  commercial  dentists  to  cater  to  and  supply  the  demand,  a  large 
variety  of  ready-made  seamless  crowns,  in  gold  and  aluminum,  are  pro- 
curable ad  libitum. 

They  are  made  of  moderately  typical  form,  in  a  gradation  of  sizes,  of 
22  karat,  30  gauge  gold,  and  about  26  or  28  gauge  aluminum,  and  in  their 
use  a  measurement  of  the  root  is  taken  and  a  crown  selected  which  ap- 
proximates the  same  diameter.  The  cervix  is  then  trimmed  until  a  closure 
of  the  occluding  teeth,  with  it  in  position,  is  possible,  when  it  is  fitted  to 
the  root  with  pliers,  and,  if  of  gold,  rc-enforced  with  solder  and  mounted. 

The  most  accurate  method  of  fitting  a  ready-made  gold  crown  to  a 
root  is  to  cut  a  slit  in  each  approximal  surface,  lap  the  edges,  place  the 
crown  on  the  natural  root  and  contract  its  cervical  circumference  by  en- 
circling the  crovv'n  with  annealed  German-silver  or  copper  wire  and  twist- 
ing the  wire  till  the  band  is  in  good  contact  with  the  root.  Adaptation  is 
further  perfected  by  burnishing,  after  which  the  slits  are  united  with 
solder. 

That  such  crowns  may  be  correctly  adapted  to  all  the  requirements 
of  all  environments  is  doulitless  a  claim  which  no  conscientious  skil- 
ful operator  would  make,  because,  while  their  individual  formation  is 
fairly  typical  of  the  natural  teeth,  it  is  difficult  to  conceive  of  securing  a 
ready-made  form  which  can-  be  adapted  to  the  requirements  of  cervical 
adaptation,  approximal  restoration,  occlusion  and  alignment,  all  combined. 

Indeed,  these  requirements  are  often  difficult  to  obtain  in  a  crown 


126 

which  is  made  for  the  individual  case,  and  at  the  expense  of  every  degree 
of  energy,  skill  and  handicraft  possessed  by,  and  at  the  command  of,  the 
operator. 

The  progress  of  dentistry,  and  the  artistic  possibilities  pertaining  to 
it,  have  only  been  achieved  by  the  development  of  a  superior  skill  v^hich 
cannot  be  acquired  by  the  adoption  of  such  indifferent  methods. 

Ketnoi^ind  dnd  Repairind. 

As  a  result  of  pathological  disturbances  arising  beneath  them,  or 
for  the  purpose  of  substitution  or  replacement,  it  not  infrequently  becomes 
necessary  to  remove  a  gold  crown  from  its  attachment  to  the  root. 

In  the  presence  of  conditions  demanding  therapeutic  treatment,  it  L 
sometimes  possible  to  cut  through  the  occlusal  surface  of  the  crown  on  a 
line  with  the  pulp  chamber,  with  a  sharp,  spear-point  drill  or  round  bur, 
and  then  enlarge  the  opening  until  adequate  access  to  the  canals  is  se- 
cured.   The  necessary  treatment  may  then  be  made  through  this  opening, 


upon  the  completion  of  which  the  pulp  chamber  and  crown  may  be  filled 
with  cement,  and  a  gold  filling,  anchored  in  the  cement,  subsequently  m 
sorted  until  the  opening  is  imperviously  closed. 

While  such  a  procedure  may  be  productive  of  successful  results  in 
some  instances,  particularly  in  bicuspids  or  single-rooted  teeth,  it  should 
not  be  regarded  as  a  safe  one  in  most  cases,  because  the  presence  of  the 
crown  only  adds  to  the  difficulties  to  be  encountered  in  an  operation  which 
is  usually  trying  enough  under  the  most  favorable  circumstances,  and  with 
every  advantage  of  access  and  light. 

For  this  reason  the  removal  of  the  crown  is  almost  invariably  indi- 
cated as  a  means  of  affording  greater  convenience  and  increased  oppor- 
tunities for  success,  and  may  be  easily  accomplished  in  two  ways. 

Where  it  is  not  necessary  to  preserve  the  con- 

Crown  $]itting        tinuity   of   the   band   for  subsequent   replacement  oi 
Torccps,  the  crown,  and  in  emergency  cases  where  its  imme- 

diate removal  is  indicated  or  demanded  as  a  means  of 
affording  relief,  the  crown  slitting  forceps  may  be  used  to  good  advan- 


127 

tage.  Those  designed  by  the  S.  S.  White  and  the  ConsoUdated  Dental 
Manufacturing  Companies,  the  application  of  which  latter  is  shown  in 
Fig.  113,  are  especially  useful  in  securing  the  easy  and  expeditious  de- 
tachment of  the  crown  from  the  root. 

In  their  use  the  flat  beak  should  rest  firmly  upon  the  crown,  and  the 
sharpened  one  caught  just  under  the  edge  of  the  band,  when  a  slight 
compression  of  the  handles  will  quickly  separate  it.  The  band  may  then 
be  pried  away  from  the  root  with  a  smooth  flat  burnisher  until  a  pointed 
instrument  can  be  slipped  in  between  cusp  and  root  and  the  crown  lifted 
off,  which  may  also  be  often  done  with  the  forceps  alone. 

When  the  same  crown  is  to  be  replaced,  it  may 

PreserPlltfl  be  desirable  to  remove  it  without  destroying  the  con- 

dontinuitV  OT  Band,    tinuity    and    shape    of    the    band,    thus    distorting 

its  adaptation.     This  may  be  easily  accomplished  by 

drilling  through  it  with  a  round  bur  at  a  convenient  point,  as  close  to  the 

occlusal  surface  as  the  probable  thickness  of  the  cusp  will  admit  (Fig. 


F/cfJI4. 

114),  and  then  burring  out  as  much  of  the  cement  detween  cusp  and  root 
as  possible  by  a  lateral  movement  of  the  bur,  A  stiff,  blunt-pointed  in- 
strument, similar  to  an  old  hand-plugger,  should  now  be  inserted  into 
the  opening,  until  its  end  rests  about  on  the  center  of  the  root,  thus  secur- 
ing a  leverage  by  the  establishment  of  a  fulcrum,  when  the  crown  may  be 
lifted  off  with  but  little  effort. 

While   a   crown   removed   with   the    slitting    forceps 
K^pairinfl  may  be  easily  repaired,  as  no  material  is  destroyed, 

it  is  doubtful  if  the  edges  so  cut  can  be  again  brought 
into  proper  relation  and  contact  without  requiring  a  readaptation  to  the 
root  in  case  of  replacement.  Aside  from  this,  the  two  procedures  may  be 
interchangeable  and  can  be  used  as- convenience  and  requirements  may 
seem  to  indicate. 

In  either  event,  when  repair  is  necessary,  all  remaining  cement  should 
be  first  removed  with  a  bur,  and  the  crown  then  thoroughly  cleaned  in 
acid,  when  the  perforations  may  be  filled  with  foil  gold,  and,  together 
with  other  openings,  then  finally  closed  with  18  karat  solder. 


Oc  Sbcll  or  telescope  grown  in  eomDinntion  will)  Porcelain. 


CHAPTER    VIII. 

Indications.     Application  to  Anterior  Teeth :    Jacket    Crowns ;    IMalformed    Teeth, 
Extensive   Abrasion,   Procedure ;   Band,  Facing,  Backing,  Soldering.     Appli- 
cation to  Irregularities.  Application  of  Facings  to  Bicuspid  Crowns : 
Procedure;  Preparing  Crown   for     Reception     of     Porcelain, 
Adapting  Facing,  Adapting  Backing,  Soldering  Backing, 
Soldering    Facing.      Variation  of  Method.      Applica- 
tion of  Saddle-back  Teeth   to   Bicuspid   and 
Alolar  Crowns:  Procedure.     Dowels. 


The  application  of  porcelain  facings  to  crown  construction,  wherein 
the  shell  or  telescope  principle  of  attachment  to  root  is  employed,  involves 
several  varied  methods  and  processes,  many  of  which  are  often  indicated 
in  special  classes  of  cases,  and  may  be  productive  of  practical  and  artistic 
results. 

While  the  modern  application  of  the  ceramic  art  doubtless  offers  far 
greater  opportunities  for  more  aesthetic  and  hygienic  achievements  in  this 
line  of  work,  the  essential  requirements  of  strength  as  applied  to  the 
method  of  attachment  to  the  root,  as  well  as  to  the  completed  crown,  are 
factors  not  infrequently  contraindicating  its  use.  These,  together  with  the 
absence  of  facilities,  or  the  lack  of  experience  and  skill,  may  often  indicate 
the  combination  of  gold  and  porcelain  as  a  means  of  obtaining  increased 
strength,  and  of  securing,  or  more  closely  approaching,  the  desired  artistic 
and  aesthetic  result. 

The  application  of  this  style  of  crown  construc- 
Tndications.  tion  is  especially  indicated  in  that  class  of  cases  where 

it  seems  desirable,  or  becomes  necessary  to  utilize  a 
portion  of  the  remaining  natural  crown  for  the  attachment  of  the  artificial 
substitute,  by  telescoping  it  instead  'of  sacrificing  it  to  the  gum  line  and 
employing  a  dowel ;  and  where  the  presentation  of  porcelain  is  essential 
to  the  artistic  requirements. 

Those  conditions  in  which  these  combined  requirements  are  par- 
ticularly applicable,  and  the  preferable  and  most  practical  methods  of 
subserving  them,  will  be  considered  in  their  respective  classification. 


129 

Jlppllcation  to  ^Interior  CeetD. 

The  application  of  this  style  of  crown  to  the  six  anterior  teeth,  upper 
or  lower,  is  frequently  indicated,  but  should  be  made  only  in  the  absence 
of  a  better  method,  and  in  accordance  with  the  judgment  and  discretion 
of  experience,  because  the  practicability  of  the  principles  involved  has  been 
much  abused  by  the  indiscriminate  and  too  extensive  use  of  the  design 
known  as  the  jacket  crown. 

The  so-called  jacket  crown  is  often  a  most  use- 
Jacket  Crowns.  ful  style  of  construction,  but  is  particularly  so  in  the 
restoration  of  malformed  crowns  of  teeth,  as  pre- 
viously indicated  in  Fig.  29,  and  in  conditions  of  extensive  abrasion. 
As  the  proportions  of  the  remaining  natural  crown,  however,  are  ordi- 
narily retained  at  the  expense  of  the  strength  of  the  artificial  substitute, 
because  of  the  limited  amount  of  space,  the  requirements  of  occlusion  and 
alignment  must  be,  or  be  made,  favorable  to  the  reception  of  a  crown 
possessing  sufficient  strength  to  withstand  the  stress.  For  this  reason 
the  use  of  gold  in  combination  with  porcelain  facings  usually  affords 
greater  strength  than  all-porcelain  work. 

In  the  restoration  of  the  crowns  of  malformed 
malformed  ZaXY),  teeth  the  use  of  the  jacket  crowm  is  particularly  ap- 
plicable because  of  the  usual  favorable  shape  and 
formation  of  the  natural  crown ;  and  for  the  reason  that  it  is  often  de- 
sirable to  preserve  the  vitality  of  the  pulp  in  such  teeth,  because  of  the 
probable  unfavorable  length  and  imperfect  development  of  the  root,  which 
might  often  preclude  securing  adequate  mechanical  attachment  of  a  dowel 
crown. 

In  such  conditions  the  destruction  of  the  natural  crown  would,  ol 
course,  be  of  doubtful  advantage,  and  sometimes  even  unwarrantable ;  and 
the  preservation  of  the  vitality  of  the  pulp  presents  a  favorable  prognosis 
because  usually  so  little  mechanical  preparation  would  become  necessar\ 
that  no  great  shock  or  irritation  would  be  induced,  and  the  dentine  is 
not  deprived  of  the  protection  of  its  coat  of  enamel. 

This  style  of  crown  is  also  frequently  indicated 
Extensive  Jlbraslon.  as  a  means  of  arresting  the  destructive  influences  01 
abrasion,  and  restoring  the  natural  crown  in  a  useful 
and  aesthetic  manner.  If  the  occlusion  in  such  cases  is,  or  may  be  made, 
favorable  for,  and  the  requirements  indicate  the  use  of,  porcelain  facings, 
the  preservation  of  the  remair-ng  natural  crown  may  afford  the  advantage 
of  a  more  accurate  and  perfect  reproduction  of  the  occlusal  surfaces,  and 
at  the  same  time  adequate  stability  to  the  attachment  of  the  crown. 

The  advisabilitv  of  destroying  the  vitality  of  the  pulp  in  these  case? 
is  much  a  matter  of  judgment,  but  is  not  always  essentially  a  prophylactic 


I30 

measure,  because  such  conditions  are  not  usually  found  in  early  life. 
Hence,  as  a  result  of  the  combined  influences  of  age  and  continued  at- 
trition, the  pulps  have  usually  receded,  and  the  canals  are  not  infrequently 
found  to  be  partially  or  entirely  obliterated.  The  degree  of  sensitiveness 
manifested  during  the  necessary  mechanical  preparation  will  serve  as  a 
guide,  however,  :n  indicating  the   requirements  in  this  connection. 

The  first  procedure  constitutes  the  preparation 
Procedure.  of  the  remaining  natural  crown  until  its  periphery 

presents  a  favorable  shape  for  the  accurate  adapta- 
tion of  a  band,  and  the  labial,  lingual  and  incisal  surfaces  are  sufficiently 
reduced  to  afford  accommodation  for  a  facing,  and  admit  of  a  favorable 
occlusion.     (Fig.  115,  a.) 


F/g.//5. 


A  band  of  about  30-gauge  22-karat  gold  should 
Band.  then  be  fitted  to  the  root,  passing  just  freely  beneath 

the  gum.  After  completing  the  adaptation  of  the  cer- 
vical end,  the  labial  portion  should  be  cut  away  on  a  gradual  slope,  closely 
following  this  surface  of  the  remaining  crown,  until  the  facing  may  be  car- 
ried to  the  gum  line.  The  lingual  portion  of  the  occlusal  end  should  then 
be  trimmed  until  it  offers  no  interference  to  the  occlusion,  after  which  the 
interior  of  the  band,  in  position  on  the  root,  should  be  filled  even  to  its 
edge  with  wax,  and  the  bite  and  impression  secured. 

When  the  model  has  been  obtained  and  mounted 
Tricing.  upon  the  articulator,  a  facing  of  the  thin  neck  va- 

riety of  mould  (Fig.  115,  b.)  should  be  selected  and 
ground  to  place,  with  a  slight  allowance  for  the  thickness  of  the  backing. 

Pure  gold,  34  to   36-gauge,   should  be  closely 
Backing.  adapted  to  the  entire  lingual  surface  of  the  facing, 

so  as  to  join  or  come  in  direct  contact  with  the  band 
along  its  laljial  and  cervical  edge  when  adjusted  to  position  (Fig.  115,  c). 
When  the  backing  has  been  properly  burnished  and  trimmed,  and  anchored 
to  the  facing  l)y  l^ending  the  ])ins,  the  band  should  l)c  detached  from  the 
model,  then  replaced  in  position  and  the  proper  relation  between  it  and 
the  facing  sustained  with  adhesive  wax.    The  joint  between  the  band  and 


oacking  should  also  be  filled  with  melted  wax  as  a  means  of  keeping  it 
clean  and  facilitating  the  subsequent  union  of  the  two  with  solder. 

When  invested,  the  wax  should  be  removed  and 

Soldering.  a  small  cap  of  22-karat  or  pure  gold  closely  fitted  to 

the  interior  edge  of  the  band.    The  case  should  now 

be  fluxed,  heated  and  soldered,  with  as  much  re-enforcement  and  contour 

as  the  occlusion  will  permit.     (Fig.  115,  d.) 

In  cases  where  a  broad,  flat  contact  surface  for  the  opposing  teeth 
may  be  required,  successive  layers  of  clasp  metal  may  be  attached  with 
solder  until  a  favorable  occlusion  is  secured.  In  this  event  the  incisal 
end  of  the  thin  pure  gold  backing  must  be  also  adequately  re-enforced 
with  solder,  though  a  better  method  of  backing  for  such  cases  will  be 
subsequently  considered. 

It  will  be  noted  that  the  adaptation  of  the  crown  to  the  projecting 
conical  end  of  the  natural  tooth  is  not  close,  but  a  closer  conformation  is 
usually  unnecessary  if  the  cervical  edge  fits,  as  the  increased  quantity  of 
cement  thus  used  in  mounting  adds  materially  to  the  strength  of  the 
attachment. 

If,  for  any  reason,  a  more  perfect  adaptation  may  seem  indicated,  or 
desirable,  it  may  be  easily  secured  by  burnishing  or  swaging  a  cone  of 
pure  gold,  34  to  36  gauge,  or  platinum  foil,  i-iooo  in  thickness,  to  the 
tooth  in  the  mouth,  after  the  band  has  been  fitted  and  trimmed ;  then 
adjusting  first  the  cone  and  then  the  band  to  position,  removing  them 
in  situ,  with  their  relation  sustained  with  wax,  and  investing  and  solder- 
ing them,  when  the  crown  may  be  completed  as  indicated. 

Such  a  procedure  is  seldom  required  or  even  warrantable,  however, 
because  so  little  cement  could  be  used  in  mounting  that  a  more  or  less 
weak  attachment  would  necessarily  result.  While  the  simple  telescoping 
cone  is  sometimes  used  without  the  band,  the  latter  is  essentially  advan- 
tageous as  a  means  of  securing  sufficient  strength  at  the  cervical  end 
and  adequate  adaptation  to  the  root  beneath  the  gum. 

When  the  crown  has  been  finished  and  polished,  the  remaining  natu- 
ral tooth  should  be  roughened  or  slightly  serrated  with  a  thin  edge  stone, 
or  sharp  bur,  before  mounting,  as  such  a  procedure  offers  a  mechanical 
supplement  to  the  adhesive  properties  of  tl:e  cement,  which  affords  in- 
creased strength  in  the  attachment. 

Jlpplicdtion  to  Trregularities. 

The  jacket  crown  may  also  be  found  occasionally  useful  in  the  treat- 
ment of  irregularities,  where  the  character  and  position  of  the  teeth,  and 
the  age  of  the  patient,  may  not  warrant  the  usual  procedure  for  their  cor- 
rection. 


132 

The  method  advocated  by  Dr.  George  Evans  is  illustrated  in  Fig. 
ii6,  and  consists  of  constructing  a  gold  crown  for  the  malposed  tooth, 
and  then  attaching  a  facing  to  it  by  means  of  a  heavy  round  wire,  so 
adjusted  as  to  carry  the  facing  in  its  proper  relation  to  the  adjacent  teeth, 
and  to  be  free  of  the  occlusion. 

The  more  or  less  conspicuous  appearance  of  the  gold  crown,  even 


Fig.  11 6. 


though  partially  hidden  by  the  facing,  is  an  objectionable  feature,  how- 
ever, and  equally  useful  and  more  artistic  results  could  be  usually  ob- 
tained by  sacrificing  the  natural  crown  and  adapting  a  dowel  crown  to 
support  the  facing  in  its  proper  position. 

Jlpplicatioit  of  Taciitds  to  Bicuspid  €rown$. 

As  a  means  of  eliminating  the  objectionable  and  conspicuous  display 
of  gold  in  crowning  the  bicuspid'^;,  the  application  of  porcelain  facings  to 
gold  crowns  is  frecjuently  indicated,  and,  if  skilfully  executed,  approaches 
the  more  artistic  results  achieved  in  the  use  of  porcelain  work,  or  dowel 
crowns. 

While  various  methods  are  advocated  and  employed,  a  slight  modi- 
fication of  the  one  suggested  by  Dr.  Hollingsworth  meets  the  requirements 
in  the  most  practical,  artistic  and  expeditious  manner. 

In  the  procedure  the  gold  crown  should  be  first 

Procedure.  constructed  by  any  of  the  various  methods  in  which 

the  swaged  cusp   is  used,  but  the  band  and   cusps 

should  be  soldered  with  22-karat  solder,  and  no  re-enforcement  of  the 

cusp  made  at  the  time  of  vmiting  it  to  the  band. 

When  thus  completed,  and  roughly  finished,  the  root  should  receive 
further  and  proper  preparation  for  the  accommodation  of  the  porcelain 
facing.  This  constitutes  sacrificing  the  buccal  surface  on  a  gradual  slope 
to  the  lingual,  at  an  angle  sufficient  to  admit  of  the  presence  of  the  facing 
when  placed  in  position  on  the  crown,  as  previously  illustrated  in  Fig.  40. 


^33 

The  crown  should  now  be  adjusted  to  the  root 

Pfepariitfl  Crown      and  the  outline  of  the  exposed  area,  to  be  occupied 

for  Reception         by  the  facing,  marked  in  the  gold  with  a  sharp-pointed 

Of  Porcelain.  instrument,  and  subsequently  cut  out  with  a  fine  saw, 

as  indicated  in  Fig.  117,  a. 
After  filing  the  edge  smooth  and  even,  with  the  convex  surface  of 
a  fine  half-round  gold  file,  a  thin  cuspid  facing  of  proper  size  and  color 
should  be  selected  and  ground  to  place. 


■  While  the  grinding  may  be  done  on  models, 
JTdaptins  facing.  when  necessity  or  occasion  requires,  the  most  accu- 
rate results  can  be  accomplished  by  filling  the  in- 
terior with  wax,  when  in  position  on  the  root,  and  completing  the  adapta- 
tion in  the  mouth.  In  grinding  to  the  necessary  alignment,  and  approxi- 
mation with  the  edge  of  band,  care  should  be  exercised  to  avoid  sharp 
angles  and  any  unnecessary  weakening  of  the  pins. 

When  the  desired  adaptation  has  been  completed, 
JIdapting  Bacl{ing.  a  sufficient  allowance  for  the  thickness  of  the  backing 
should  be  made  by  further  grinding  the  facing  or 
the  band,  or  both ;  and  the  facing  then  backed  up  with  pure  gold,  about 
34  gauge.  In  the  adaptation  of  the  backing  a  small  surplus  should  be 
allowed  to  project  beyond  the  facing  at  all  points  (Fig.  117,  b),  and  care 
must  be  exercised  to  avoid  overlapping  it.  to  accomplish  which  it  may 
sometimes  be  necessary  to  cut  out  a  small  \'-shaped  piece  at  each  occlusal 
angle. 

The  facing  and  backing  should  now  be  placed  in 
Soldering  Backing,  position  on  the  crown,  and  a  sharp  instrument  passed 
around  the  buccal  edge  of  the  crown,  marking  the 
proper  relation  between  it  and  the  backing  (Fig.  117,  c),  after  which  it 
should  be  detached,  and  the  backing  soldered  to  the  crown  from  the 
outside  with  20-karat  solder,  using  enough  to  form  a  smooth  joint,  which 
may  finish  down  flusJi  with  the  porcelain  when  the  surplus  is  removed  ; 


134 

and  the  necessary   re-inforcement   of  the  cusps   should  be  made  at  this 
time. 

The  proper  relation  between  the  parts  may  be  most  easily  and  securely 


Fiq.  118. 


sustained  while  soldering  by  the  use  of  pliers  similar 
'in  design  to  those  previously  recommended  for  attach- 
ing cusps,  or  the  ordinary  nickel  automatic  soldering 
tweezers  may  be  used  by  bending  one  end  at  right  angles, 
as  indicated  in  Fig.  ii8. 

When  the  soldering  has  been  completed,  the  fac- 
ing should  be  adjusted  to  position  and  the  surplus 
trimmed  down  until  a  smooth  edge  presents  between 
crown  and  facing,  being  careful  to  avoid  any  over- 
hanging edges  of  metal  upon  porcelain. 

While    the    permanent    reten- 
Soldering  Taciltg.       tion  of  the  facing  may  be  secured 
by  bending  the  pins  down  against 
the    backing,    on    the    inside    of    the    crown,    greater 
strength  will  be  obtained  by  soldering,  on  account  of 
the   extreme  thinness   of  the   backing.     This   may  be 
quite   easily   accomplished   by   first   bending  the   pins 
F/O  1/9  down  close  upon  the  backing,  and  then  wrapping  the 

crown  with  one  thickness  of  asbestos  paper,  with  the 
occlusal  end  folded  together,  and  the  whole  held  in  place  by  wiring. 
The  backing  and  pins  should  then  be  fluxed,  preferably  with  liquid  flux, 
and  a  sufficient  quantity  of  i8-karat  solder  also  fluxed,  and  placed  in 
position.  This  should  now  be  carried  to  the  flame,  with  the  porcelain 
downivard,  and  gradually  brought  to  the  point  of  greatest  heat  (Fig. 
119),  when  a  small  flame  from  the  blow-pipe  may  be  directed  upon 
the  facing  until  the  solder  fuses,  which  can  be  readily  observed  from  the 
open  cervical  end. 

While  this  or  any  other  style  of  investment  is  rot  altogether  neces- 
sary, if  extreme  care  be  exercised  in  subjecting  the  crown  to  the  heat,  the 


135 

use  of  asbestos  paper  possesses  the  advantage  of  absorbing  but  little,  if 
any,  heat,  and  of  precluding  the  possibility  of  fracturing  the  facing,  by 
distributing  it  evenly. 

When  the  soldering  has  been  completed,  the  crown  should  be  treated 
to  the  acid  bath,  and  then  finally  polished  (Fig.  117,  d),  and  mounted. 

If  an  undue  prominence  of  the  root  interferes  with  its  proper  adjust- 
ment, it  may  become  necessary  to  sacrifice  more  from  the  buccal  surface, 
but  the  lingual  surface  should  always  be  allowed  to  remain  as  long  as 
possible,  in  order  to  afford  the  greatest  degree  of  strength  to  the  at- 
tachment. 

Another  process  or  method  productive  of  prac- 
Uafiation  Of  ni(tI)OCl.    tically  the  same  results,  but  entailing  a  different  pro- 
cedure, is  employed  by  many.     This  constitutes  first 
making  the  band,  and  fitting  it  to  the  root,  and  then  cutting  out  the  buccal 
surface  to  accommodate  the  facing  as  indicated  in  Fig.  120,  a. 


b  c 


The  usual  bite  and  impression  should  now  be  taken  and  the  models 
secured  and  mounted  upon  the  articulator.  A  cuspid  facing  of  suitable 
size  and  color  is  then  ground  to  place  until  the  proper  alignment,  and  a 
perfect  joint  with  the  cervical  and  approximal  edges  of  the  band,  are 
secured.  After  backing  the  facing  with  30-gauge  22-karat  gold,  and 
bending  the  pins  (Fig.  129,  b),  the  band  should  be  detached  from  the 
model,  the  facing  placed  in  position  upon  it.  and  their  relation  sustained 
with  a  nuniitc  quantity  of  fluxed  wax.  Asbestos  paper  should  now  be 
wrapped  around  the  parts  and  ^^'''■ed,  as  indicated,  and  the  joint  between 
the  two  filled  with  20-karat  solder  (Fig.  120,  c). 

This  portion  of  the  crown  should  now  be  readjusted  to  the  models, 
and  the  cusps  formed  to  fit  the  band  and  facing,  and  meet  the  require- 
ments of  occlusion,  after  which  they  should  be  filled  with  i8-karat  solder. 

In  attaching  the  cusps  to  the  band  and  facing  they  should  be  first 
retained  in  proper  relation  by  the  use  of  a  small  quantity  of  fluxed  wax. 
Asbestos  paper  should  now  be  wrapped  around  the  crown  with  the  oc- 
clusal end  knuckled  in  close  to  the  cusps,  and  then  wired  securely  to  place 


136 

by  twisting  the  wire  very  taut  around  the  approximal,  occlusal  and  cer- 
vical surfaces^  to  sustain  the  relation  of  the  cusps,  as  well  as  having  an 
additional  piece  of  wire  pass  around  the  center  of  the  crown  to  hold  the 
paper  together. 

With  the  surplus  ends  of  the  wire  projecting  from  the  cervical  end 
of  the  crown,  it  may  be  carried  to  the  flame,  cusps  dozvnzvard,  and  so  held 
until  the  solder,  already  in  the  cusps,  has  re-fused  and  united  with 
the  band. 

If  insufHcient  solder  has  been  placed  in  the  cusps  to  accomplish  union 
in  such  manner,  more  may  be  added  at  this  time,  and,  as  in  the  previously 
mentioned  method,  if  any  danger  of  re-fusing  or  unsoldering  joints, 
already  made,  seems  probable,  the  same  can  be  overcome  and  prevented 
by  first  coating  them  with  a  solution  of  whiting  in  alcohol  or  water,  or 
other  similar  means. 

After  soldering,  the  crown  should  be  allowed  to  cool  slowly  and 
gradually,  and  then  may  be  removed  from  the  investment,  finished  and 
polished  (Fig.   120,  d). 

While  such  crowns  may  be  invested  in  ordinary  investment  material, 
the  soldering  can  be  accomplished  with  equal  facility  and  accuracy,  and 
much  more  easily,  in  this  manner. 

Jlpplicdtion  of  $dddlc-back  Cectb  to  Bicuspid  and  molar  Crowns. 

The  application  of  the  saddle-back  tooth  to  the  construction  of  bi- 
cuspid and  molar  crowns  is  sometimes  practicable  as  a  means  of  admitting 
of  the  shell  or  telescope  principle  of  attachment,  and  of  affording  an  ar- 
tistic and  aesthetic  result,  because  of  presenting  an  occlusal  surface  of 
porcelain. 

The  element  of  strength  possessed  by  such  a  crown,  however,  depends 
much  upon  the  extent  of  space,  and  the  force  of  the  masticating  stress, 
in  the  individual  case,  as  the  lingual  cusps  are  weak  points,  unless  suf- 
ficient space  exists  so  as  to  require  but  little,  if  any,' grinding,  and  adequate 
opportunity  is  offered  for  protecting  and  supporting  them. 

In  the  procedure  incident  to  the  construction  of 
Procedure.  such  a  crown,  the  band  should  be  made  and  fitted 

in  the  same  manner  pursued  for  an  all  gold  crown, 
and  the  bite  and  impression  then  taken. 

The  root  should  be  afterward  trimmed  to  accommodate  the  presence 
of  the  porcelain. 

When  the  models  are  mounted  upon  the  articulator,  a  saddle-back 
tooth  (Fig.  121,  A),  the  occlusal  surface  of  which  approximates  the  size 
and  proportions  of  the  band,  sbould  be  selected.  In  no  instance  should 
the  porcelain  be  much  smaller  than  the  diameter  of  the  band,  but  in  the 


event  of  its  being  too  large  it  may,  of  covirse,  be  ground  to  proper  pro- 
portions. 

The  band  should  now  be  detached  from  the  model  and  cut  away  with 
curved-pointed  shears  to  admit  of  the  proper  adjustment  of  the  porcelain 
(Fig.  121,  b). 

The  porcelain  should  then  be  carefully  ground  until  it  meets  the  re- 
quirements of  alignment  and  occlusion,  comes  in  contact  with  the  remain- 
ing cervical  edge  of  the  band,  and  fits  into  the  interior  of  the  lingual  and 
occlusal  portion. 

It  should  now  be  backed  up  with  pure  gold,  about  34  gauge,  securely 
attached  by  bending  the  pins  (Fig.  121,  c),  and  then  placed  in  position 
on  the  band,  and  the  proper  relation  sustained  with  melted  wax. 

After  filling  the  interior  with  soft  wax  to  keep  it  clean,  the  crown 
should  then  be  invested  by  submerging  it  in  a  slight  covering  of  invest- 
ment material,  leaving  only  the  wax  exposed. 


Upon  removing  the  wax  the  interior  of  the  crown  will  be  exposed, 
when  flux  can  be  applied  and  sufficient  solder  placed  over  the  pins  and 
around  the  joint.  The  case  should  then  be  gradually  heated  to  a  red 
heat,  when  a  small  flame  from  the  blow-pipe,  directed  into  the  crown,  will 
quickly  accomplish  the  soldering. 

When  removed  from  the  investment  and  subjected  to  the  acid  bath, 
the  band  should  be  burnished  up  closely  to  the  porcelain,  and  the  crown 
finished  and  polished  (Fig.  121,  d). 

In  the  application  of  crowns  constructed  by  these 
Dowels.  latter  methods,  the  shortness  of  the  root  ma}-  some- 

times indicate  the  use  of  a  dowel  as  a  means  of 
supplementing  the  band  and  affording  a  stronger  attachment  to  the  root. 
When  this  is  required,  or  seems  desirable,  it  should  be  first  fitted  to  the 
canal  and  a  projecting  end  extended  into  the  lingual  portion  of  the  crown 
as  far  as  its  proper  adjustment  will  admit.  The  dowel  should  then  be 
cemented  to  place  in  the  root,  and  the  crown  separately  and  subsequently 
mounted. 


tbe  Band  and  Dowel  grovpn. 


CHAPTER   IX. 

Indications.  Requirements  :  Mechanical,  Esthetic  ;  Cervical  Curvature,  Alignment, 
Color  and  Harmony,  Oil  Colors,  iManufacturers'  Products.  Dental  Labora- 
tories. Method  of  Construction:  Procedure;  Bands,  Soldering,  Fitting.  Form- 
ing Cap.  Dowels.  Bite.  Impression.  Adaptation  of  Facing ;  Cervical  E.id, 
Incisal  or  Occlusal  End.  Backing  of  Facing;  Adaptation.  Re-enforcement. 
Soldering,  Finishing.  Variation  in  Method.  Use  of  Platinum.  Investing. 
Soldering.  Finishing.  Application  of  Partial  Bands :  Comparative  Advantages, 
Indications,  Procedure.  Application  of  Riveted  Facings:  Procedure,  Riveting. 
Application  of  Detachable  and  Replaceable  Facings:  Advantages  Claimed,  Ad- 
vantages Considered,  Advantages  Obtainable,  Various  Designs;  Mason's  Facing; 
Application.  Roach's  Facing;  Application.  Dwight's  Facing;  Application.  Bry- 
ant's Method :  Application  ;  Box  Method,  Tube  Method.  Davis  Crown.  Applica- 
tion to  Bicuspids  and  Molars:  Indications;  Bicuspids,  Molars.  Procedure; 
Re-enforced  Cap,  Use  of  Two  Dowels,  Bite  and  Impression.  Use  of  Flatback 
Facing,  Facing,  Cusps,  Adaptation,  Approximal  Restoration,  Investing,  Solder- 
ing. Use  of  Saddle-Back  Teeth :  Procedure.  Use  of  Vulcanite  Teeth.  Ap- 
plication of  Removable  Crowns.  Application  to  Irregularities:  Indications; 
Malposition,  Construction,  Extension  for  Support  of  Facing,  Hygienic  Con- 
siderations. Diminution  of  Normal  Space;  Separation  of  Teeth;  Application 
of  the  Intradental  Band;  William's  Method,  Application;  Cigrand's  Method, 
Application.  Repairing:  Replacement  of  Facings;  Usual  Method,  Procedure. 
Brewer's  Method;  Application.  Underwood's  and  Mitchell's  Method;  Applica- 
tion. Dwight's  Method;  Application.  Bryant's  Method;  Application.  Replac- 
ing Bicuspid  and  Molar  Facings.  Replacement  of  Facing  and  Backing;  Proce- 
dure. Removing;  Use  of  Excising  Forceps,  Separating  Cap  and  Dowel;  Ac- 
curacy in  Model  Making,  Improved  Articulators. 


The  usefulness  and  seviceability  of  the  band  and  dowel  crown  in  the 
various  phases  of  its  present  application  and  construction  account  for  its 
extensive  employment,  and  warrant  giving  special  emphasis  to  the  detail 
of  the  respective  methods  advocated. 

While  the  primitive  application  of  a  band  as  applied  particularly  to 
the  construction  of  anterior  crowns,  and  combined  with  a  dowel  and  porce- 
lain tooth  or  facinj(,  was  prol)ably  first  sug'gested  by  Dr.  C. 
M.   Richmond,   the    present    methods    of    construction,    and    the    facil- 


139 

ities  for  accomplishing  the  requirements,  have  so  modified  the  original 
design  as  to  cause  its  complete  aban  lonment,  and  the  adoption  of  a  proce- 
dure more  practical,  artistic  and  expeditious. 

As  there  have  been  innumerable  processes  proposed,  only  the  more 
practicable  of  those  now  in  use  will  receive  attention. 

Indications. 

Because  of  the  necessary  use  of  porcelain  for  esthetic  reasons,  and 
of  the  additional  strength  and  stability  in  the  attachment  afforded  by  the 
presence  of  a  band,  together  with  the  hermetical  sealing  of  the  root  and 
the  safeguard  against  fracture,  this  style  of  construction  is  indicated  in, 
and  universally  applicable  to,  the  restoration  of  the  ten  anterior  teeth, 
and  not  infrequently  the  first  molars.  Within  the  sphere  of  its  applica- 
tion it  occupies  the  same  degree  of  general  utility,  and  offers  the  same 
assurances  of  favorable  permanency  as  does  the  gold  crown  in  the 
restoration  of  posterior  teeth. 

Requirements. 

As  the  application  is  confined  to  the  range  of  vision,  the  requirements 
in  connection  with  the  construction  of  such  crowns  may  be  properly  classi- 
fied as  mechanical  and  esthetic,  and  yet  in  all  efforts  calculated  to  be  pro- 
ductive of  a  high  degree  of  permanency  and  artistic  endeavor  the  two 
cannot  well  be  disassociated. 

Whilst   it   is   now   generally   conceded   that   the 

Itlccbanical.  addition  of  a  band  to  dowel  crowns  affords  the  pre- 

viously mentioned  advantages,  it  is  also  readily 
acknowledged  that  the  mechanical  adaptation,  or  relation,  of  the  same  to 
the  end  of  the  root  must  be  uniformly  deep,  and  close  enough  to  the  per- 
iphery to  preserve  the  continuity  of  surface  between  root  and  crown  at 
the  line  of  junction  beneath  and  within  the  free  margin  of  the  gum,  so 
that  no  irritating  influence  may  result.  At  the  same  time,  it  is  almost 
equally  essential  that  the  band  should  be  sufficiently  narroiv  to 
be  entirely  invisible,  and  thus  admit  of  bringing  the  porcelain  into  close 
proximity  with  the  gingival  margin ;  and  yet  strong  enough  to  retain  its 
given  shape  and  form  during  the  process  of  fitting  and  adapting,  and 
when  subsequently  subjected  to  the  stress  of  mastication. 

The  importance  of  properly  trimming  the  end  of  the  root  to  begin 
with,  has  already  been  sufficiently  emphasized,  and  is  particularly  appar- 
ent in  the  shaping  of  anterior  roots,  because  of  their  even  more  conical 
shape.  If  this  is  neglected  in  the  slightest  degree,  the  cervical  edge  of 
the  band  must  form  a  shoulder  between  it  and  the  surface  of  the  root, 
which,  though  hidden  by  the  gum,  aft'ords  opportunity  for  the  lodgment 


I40 

and  accumulation  of  food  deposits,  the  subsequent  decomposition  of  which 
is  productive  of  a  decidedly  unhygienic  condition,  and  much  consequent 
discomfort.  While  nature  may  aid  the  indifferent,  careless  or  negligent 
operator  for  a  time,  by  covering  over  the  evidences  of  such  efforts — and 
in  this  connection  the  tissues  surrounding  roots  supporting  artificial 
crowns  cover  a  multitude  of  sins — the  result  is  inevitable ;  hence,  no  band 
at  all  were  better  than  one  which  docs  not  tit. 

In  the  esthetic  restoration  of  the  crowns  of  ante- 
€$tl)((iC$.  rior  teeth,  success,  with  all  it  implies,  is  codependent 

upon  the  ability  to  observe  the  minutest  details  in  an 
endeavor  to  simulate  nature,  and  that  degree  of  enthusiasm  and  ambition 
which  prompts  a  thorough  and  efficient  execution  of  the  artistic  require- 
ments involved. 

These  embrace  a  consideration  of  the  details  of  Cervical  Curvature, 
Alignment,  Color  and  Harmony. 

In  order  that  the  natural  cervical  curvature  of 

Gerpical  Curvature,     the  gum   tissue  should    remain  normal,  and    that  no 

metal  should  be  visible  in  the  finished  crown,  it  is 

essential  that  its  adaptation  should  be  made  with  this  requirement  in  view. 


A  common  fault  of  this  kind,  the  disregard  of  which  materially  in- 
creases the  artificial  appearance  of  the  work,  as  compared  with  the  correct 
itnd  artistic  outline,  is  illustrated  in  Fig.  122. 

The  feature  of  alignment  with  adjacent  teeth  is 
Jlliflnment  most  important,    and  particularly    as  applied  to    the 

cervical  half  of  the  crown.  A  common  fault  with 
many  crowns,  otherwise  artistic,  is  an  undue  prominence  at  the  neck, 
which  is  caused  by  not  cutting  the  labial  portion  of  the  root  short  enough, 
or  by  the  selection  of  a  facing  too  thick  or  bullions  at  this  point,  and  the 
failure  to  properly  reduce  it,  by  grinding,  before  the  completion  of  the 
crown. 

A  proper  and  equally  symmetrical  alignment  of  the  incisal  end  should 
also  be  oliserved,  and,  while  the  occlusion  may  govern  to  some  extent,  it 
is  often  permissible  to  grind  interfering  opposing  teeth  slightly  to  admit 
of  securing  this.     In  this  connection  considerable  trimming  and  shaping 


HI 

of  the  ends  and  uneven  and  irregular  edges  of  natural  teeth  may  often  be 
done  to  their  improvement  and  benefit,  and  entirely  without  harmful  or 
injurious  results,  if  done  carefully  and  judiciously,  such  surfaces  being 
afterward  polished  smooth  with  fine  disks. 

As  nothing  in  nature  is  more  apparent  than  the 
ColOf  nnd  1)arniony.     universal  expressions  of  harmony,   it  is,  of  course, 
essential  in  simulating  it  that  every  effort  should  be 
expended,    and    every    facilitity    employed,    to    obtain    this    in    the    con- 
struction of  artificial  crowns,  that  they  may  more  closely  resemble  the  re- 
maining natural  teeth. 

The  selection  of  a  tooth  or  facing  of  the  proper 

Color.  color,  with  due  allowances  for  any  change  which  may 

be  occasioned  by  the  presence  of  a  metal  backing,  or 

other  means  of  diminishing  its  translucency,  is  often  a  difficult  and  very 

exacting  problem,  and  those  who  are  so  unfortunate  as  not  to  be  endowed 

with  an  accurate  and  artistic  eye  will  often  be  seriously  handicapped. 

The  color  should  be  selected  with  these  possible  changes  in  view,  and, 
particularly  in  the  restoration  of  the  six  anterior  teeth,  should  usually 
match  the  natural  tooth  corresponding  to  the  one  being  crozvned  (if  pres- 
ent), as  a  variation  in  the  color  of  natural  teeth  in  the  same  mouth  is 
marked,  to  which  special  attention  has  been  given  in  a  splendid  contribu- 
tion by  Dr.  E.  C.  Royce,  of  Chicago.  If  some  variation  seems  unavoid- 
able, a  slightly  darker  shade  is  usually  preferable  to  a  lighter  one,  and 
effects  a  less  conspicuous  and  in  consequence  more  artistic  result. 

The  use  of  the  high-fusing  oil  colors,  introduced 
Oil  Colors.  by   Mr.   Robert   Brewster,   of  Chicago,   or  a  lower- 

fusing  variety  made  by  C.  Ash  &  Sons,  makes  it  pos- 
sible to  obtain  almost  any  desired  variation  of  shade  in  a  single  facing,  as 
well  as  to  more  perfectly  and  artistically  imitate  the  characteristics  of  the 
remaining  natural  teeth.  These  are  prepared  in  several  basal  or  primary 
colors,  and  in  obtaining  color  and  shadow  effects  are  to  be  thinlv  mixed  and 
painted  on  the  lingual  surface  of  the  facing,  immediately  after  the  grinding 
has  been  completed,  then  placed  in  the  furnace  and  fused,  after  w^hich, 
when  the  desired  result  has  been  obtained,  the  crown  is  constructed  as 
intended. 

In  reproducing  pits,  grooves,  erosion,  tobacco  stains,  etc.,  the  colors 
are  to  be  painted  upon  the  labial  surface,  after  properly  grinding,  and  then 
fired  before  backing. 

Harmony  in  shape,  form   and   characteristics   is 
1)armony.  scarcely  second  in  importance  to  color,  and  at  least 

in  salient  features  should  be  closely  observed,  as  the 
artistic  possibilities  increase  in  proportion  thereto. 


142 

The  shape  and  general  form  of  the  porcelain  tooth  or  facing  should 
be  the  same  as  the  corresponding  natural  tooth  (if  present)  ;  the  length 
from  cervical  to  incisal  edges  should  be  the  same  as  the  adjacent  teeth; 
the  angles  and  incisal  edge  should  be  characteristic  of  the  remaining  teeth, 
and  in  the  event  of  the  presence  of  numerous  and  conspicuous  gold  fillings 
the  artificial  crown  should  be  similarly  treated. 

In  complying  with  such  requirements  too  much 
manufacturers'         should    not  be    expected  of  the    manufacturers    and 
PrcdUCtS.  supply  houses,  as  it  would  be  impossible  for  their  best 

efforts  to  be  productive  of  results  which  could  rea- 
sonably be  expected  to  be  universally  adaptable  to  all  cases.  Their  prod- 
ucts represent  only  the  efforts  of  the  artisan  in  catering  to  the  general 
demand,  and  the  successful  operator  only  can  and  must  become  the  artist. 
A  selection  which  approaches  the  requirements  should  be  made,  and 
then  ground  and  shaped  as  the  characteristics  of  the  case  may  indicate.  In 


nearly  all  makes  of  porcelain  teeth  this  can  be  done  with  impunity  if  the 
surfaces  so  ground  are  afterwards  repolished  with  fine  disks,  and  the  re- 
sult is  even  more  natural  than  the  highly  glazed  surface. 

It  is  this  particular  feature  that  should  impel 
Dental  EaboratorlCS.  the  progressive,  conscientious  dentist  to  acquire  such 
skill  as  may  enable  him  to  execute  his  own  work,  for 
the  practice  of  relegating  this  class  of  work  to  dental  laboratories,  where, 
in  the  majority  of  them,  the  motto  observed  in  making  bands  is  to  have 
them  large  enough  to  admit  of  easy  and  ready  adjustment;  where  cusp- 
forms  are  made  by  the  office  boy,  by  the  score ;  where  the  color  is  but  a 
chance;  where  accompanying  instructions  that  the  bite  is  normal  will 
suffice,  and  where  lime  and  revenue  are  necessarily  the  only  serious  con- 
siderations, should  be  condemned  as  materially  retarding  the  progress  and 
advancement  of  an  artistic  field  of  professional  effort. 


143 

metboa  of  eonstructioti. 

In  a  consideration  of  the  method  of  constructing  this  style  of  crown, 
the  consecutive  stages  of  which  are  illustrated  in  Fig.  123,  special  empha- 
sis must  again  be  given  to  the  essentials  of  root  preparation,  and  particu- 
larly to  the  feature  of  allowing  the  end  to  project  about  one-sixteenth  of 
an  inch  from  the  gum  until  the  peripheral  trimming  has  been  accom- 
plished, the  measurement  taken,  and  the  hand  fitted. 

The  importance  of  this  procedure  has  already  been  sufficiently  empha- 
sized, and  cannot  be  overestimated,  as  a  neglect  to  observe  or  a  disregard 
of  it  will  add  materially  to  the  difficulties  encountered,  and  to  the  degree 
of  inaccuracy  and  discomfiture  resulting. 


-:><m 


f/c7./24. 


When   the    remaining   natural   crown   has   been 
Procedure.  cut  to  the  desired  extent,    and    the    projecting    end 

of   the     root   properly    trimmed,    the    measurement 
should  be  taken  in  the  manner  already  indicated. 

A  band  should  now  be  cut  the  exact  length  of 

Bands.  the  measurement,  about  one-eighth  of  an  inch  wide, 

and  of  22  karat  gold,  28  or  29  gauge  in  thickness. 

The  edges  should  be  filed  straight  and  smooth, 

Soldering.  and  the  band  annealed  and  made  into  circular  form. 

By  first  overlapping  and  then  abutting  the  ends,  their 

contact  may  be  sustained  when  heated,  as  already  described,  and  the  joint 

should  be  soldered    from  the  inside  with  a    minute  bit  of  22   or  20  karat 

solder. 

The  first  procedure  incident  to  fitting  the  band 

fitting.  should  be  to  give  it  a  general  shape  approximating 

that  of  the  root,  and  then  to  trim  the  cervical  edge  to 

closely  follow  the  curvature  of  the  gum,  with  the  joint  at  the  center  of  the 

lingual  surface.     Curved  pointed  plate  shears,  or  the  crown  shears  espe- 


144 

cially  designed  for  such  trimming  (Fig.  124)  may  be  used  for  this 
purpose. 

When  thus  trimmed  so  as  to  come  in  uniform  contact  with  the  gum 
when  loosely  and  temporarily  adjusted  to  the  end  of  the  root,  the  edge 
should  be  filed  smooth  with  the  convex  surface  of  a  fine  half-round  file 
(Grobet,  4  to  5  inch,  No.  5),  and  then  nicely  rounded,  always  avoiding  a 
thin  feather-edge  for  the  reasons  mentioned. 

The  band  should  now  be  placed  upon  the  projecting  end  of  the  root, 
and  then  forced  gently  to  position  with  a  small  piece  of  wood,  until  it 
passes  just  freely  beneath  the  gum.     (Fig.  125,  A.) 

While  the  topical  application  of  solutions  of  cocaine,  carbolic  acid, 
etc.,  are  frequently  relied  upon  as  a  means  of  obtunding  the  pain,  the  use 
of  any  therapeutic  agent  is  seldom  necessary  where  the  band  Hts  a  pro- 
jecting end  of  a  properly  prepared  root,  as  this  serves  to  first  conform  it  to 


Ficj.125. 


the  proper  shape,  and  then  guide  it  to  place,  thus  causing  little,  if  any,  dis- 
comfort. A  very  great  percentage  of  cases  where  any  acute  pain  is  occa- 
sioned can  usually  be  attributed  to  forcing  the  band  into  the  tissue,  instead 
of  its  closely  following  the  outlines  of  the  root,  and  passing  under  and 
within  the  free  margin  of  the  gum,  without  unnecessarily  impinging  upon 
the  periosteum  or  peridental  membrane. 

When  the  cervical  end  has  been  properly  adapted,  the  band  should  be 
removed  and  trimmed  until  the  labial  surface  is  as  narrozv  as  pos- 
sible to  meet  the  requirements,  but  gradually  sloping  until  it  is  somewhat 
wider  upon  the  lingual. 

It  should  now  be  readjusted  to  the  root  and  forced  well  to  place  until 
it  is  entirely  invisible  from  the  labial  aspect.  The  root  should  then  be 
ground  down  until  its  basal  surface  follows  the  outlines  indicated  and 
approximates  the  edge  of  the  band.      (Fig.  125,  B.) 


145 

While  this  relation  may  be  obtained  by  grinding  the  root  down  witli 
the  band  in  position,  it  is  usually  best  to  remove  the  band  during  the  pro- 
cedure, for  the  reason  that  it  may  become  loosened  from  the  vibration,  and 
slip  downward  unobserved,  thus  endangering  the  distortion  of  its  shape ; 
or,  of  being  ground  too  narrow  to  be  useful ;  and  the  heat  produced  by 
the  friction  is  also  an  objection  to  grinding  and  shaping  a  band  in  the 
mouth. 

When  thus  properly  trimmed,  it  should  be  removed  with  a  small  hook 
instrument,  and  the  floor  then  attached. 

The  floor  to  the  band,  in  the  attachment  of  which 

Tormiltd  Cap.         the  cap  is  formed,  should  be  thin  enough  to  be  easilv 

adapted  to  contact  with  the  edge  of  the  band,  and 

admit  of  bringing  the  neck  of  the  porcelain  facing  into  close  proximity 

with  the  gum. 


/.  W 


FiqJ26. 


For  this  purpose,  platinum,  about  34  gauge,  is  preferable,  as  afford- 
ing the  desired  thinness  without  danger  of  being  fused  in  the  subsequent 
final  soldering  of  the  parts ;  although  pure  gold,  or  even  gold  of  22  karat, 
of  the  same  gauge,  may  be  used. 

Any  special  degree  of  strength  in  the  floor  itself  becomes  unnecessary 
in  gold  li'ork,  because  of  the  quantity  of  solder  which  will  be  subse- 
quently used  in  uniting  cap  and  facing,  and  properly  contouring  the  lin- 
gual surface. 

In  soldering  the  floor  to  the  band,  a  liberal  surplus  of  the  metal  (gold 
or  platinum)  should  be  used,  and  will  facilitate  the  procedure.  The  band 
should  be  placed  in  the  center  of  this,  without  any  special  effort  to  secure 
a  perfect  adaptation  at  this  time,  the  parts  then  fluxed  and  attached  at  one 
point  of    contact  by  the  partial   fusion  of  a  small   bit  of  20  karat    solder 


146 

placed  outside  of  the  band.  This  will  anneal  the  floor  metal  so  that  it  may 
readily  be  burnished  to  a  perfect  contact  with  the  edge  of  the  band ;  and 
absolute  contact  around  the  entire  circumference  is  essential,  as  an  opening 
or  space  filled  only  with  solder  may  be  again  opened  by  the  re-fusing  of 
the  solder  in  the  final  assemblage  of  the  crown.  In  securing  this  contact, 
however,  care  should  be  exercised  to  prevent  changing  the  shape  and  form 
of  the  band. 

After  applying  flux,  one  corner  of  the  floor  should  be  grasped  with 
fine-pointed  soldering  pliers,  and  again  carried  to  the  flame,  until  the  com- 
plete fusion  of  the  solder  formerly  used  unites  the  parts  around  the 
entire  joint.  (Fig.  126.)  It  will  seldom  be  found  necessary  to  make  a 
second  application  of  solder,  for  the  quantity  required,  where  good  contact 
exists,  is  almost  infinitesimal. 

After  the  soldering  has  been  completed,  the  surplus  of  floor  metal 
should  be  trimmed  close  to  the  band,  and  the  joint  then  finished  down 
smooth,  with  stones  and  disks. 

When  adjusted  to  position  on  the  root,  the  cap  should  rest  firmly  upon 
its  seat,  and  any  tendency  to  rock  should  be  relieved.  Rocking  usually 
indicates  a  high  point  on  the  extreme  approximal  edge,  the  removal  of 
which  will  overcome  the  difficulty. 

Dowels. 

The  cap  should  now  be  removed,  and  the  canal  prepared  for  the  re- 
ception of  the  dowel,  the  requirements  of  which  have  been  already  out- 
lined. 

As  the  dowel  assumes  the  greater  portion  of  the  strain  to  which  the 
crown  will  be  subjected,  the  alloy  of  platinum  and  iridium  is  generally 
used,  because  of  its  toughness  and  strength;  and  the  round,  square  and 
triangular  wire,  in  sizes  varying  from  14  to  18  gauge,  according  to  that 
indicated  by  the  proportions  of  the  root,  are  prepared  for  the  purpose. 

The  so-called  "platinoid"  and  other  German  silver  alloys  are  also 
prepared  and  used  for  this  purpose,  but  the  only  advantage  possessed  by 
them  is  that  of  economy,  and  this  is  gained  at  the  expense  of  stiffness, 
strength  and  permanent  integrity. 

If  there  is  any  preference  as  to  the  form  of  wire  used,  it  is  in  favor  of 
the  round,  because  of  its  being  easier  to  remove  from  the  canal  after 
mounting,  in  case  of  necessity ;  and  of  its  being  perhaps  also  easier  to  per- 
forate the  floor  of  the  cap  in  such  manner  as  to  secure  a  close  contact 
between  it  and  the  dowel  at  the  line  of  junction,  which  facilitates  and  adds 
strength  to  their  union,  and  prevents  the  solder  from  flowing  in  upon  the 
under  side  of  the  cap.  For  this  reason  should  a  square  dowel  seem 
desirable,  round  wire,  of  heavier  gauge  may  be  used,  and  that  ]jart  which 


147 

enters  the  canal  filed  square  after  fitting  to  the  hole  in  the  floor  but  before 
soldering. 

The  advantages  claimed  for  the  square  and  triangular  forms  are  that 
a  wire  drawn  with  sharp  angles  possesses  greater  strength  and  resistance 
than  a  round  one ;  and  that  any  possible  rotation  of  the  crown  on  conical 
roots,  after  mounting,  is  precluded.  If  the  wire  used  is  of  adequate  size  to 
meet  the  requirements,  the  round  form  possesses  sufficient  strength,  how- 
ever, and  there  can  be  no  rotation,  if  the  crown  is  well  adapted  and  the 
mounting  is  secure. 

In  fitting  to  the  canal  a  length  should  be  cut  which  will  afford  some 
surplus,  and  one  end  then  slightly  tapered.  When  the  dowel  has  been 
properly  prepared  and  adapted,  the  cap  should  be  placed  in  position  and 
a  large  round  or  oval  burnisher  used  to  outline  the  opeiiing  of  the  canal, 
in  the  floor.  A  small  perforation  through  the  center  of  this  outline  should 
now  be  made  with  a  sharp  pointed  instrument,  or  bur,  and  the  dowel  then 
grasped  firmly  with  pliers  and  the  tapered  end  forced  through  the  floor 
and  into  the  canal  until  in  proper  position,  which  insures  a  close  contact 
between  dowel  and  floor. 


FiqJ21. 


When  properly  adjusted,  the  relation  should  be  at  once  permanently 
sustained  by  soldering,  to  accomplish  which  base-plate  gutta  percha,  tem- 
porary stopping,  or  adhesive  wax,  should  be  warmed  and  packed  around 
the  projecting  end  of  the  dowel,  and  over  the  surface  of  the  cap.  When 
this  is  cool,  which  may  be  hastened  by  a  spray  of  cold  water,  they  should 
be  carefully  detached  from  the  root,  and  the  interior  of  the  cap  filled  with 
plaster  or  investment  material,  until  the  dowel  is  covered.  (Fig.  127.) 
The  use  of  any  more  investment  material  than  absolutely  necessary  only 
adds  to  the  difficulty  of  soldering,  and  it  is  essential  that  it  should  be 
packed  down  into  the  cap  well  to  prevent  burning  the  band.  After  this 
investment  has  crystallized,  the  removal  of  the  temporary  medium,  by 
warming  over  the  flame,  will  admit  of  securely  attaching  the  parts  with 
solder  by  the  use  of  the  small  mouth  blowpipe. 

In  the  event  of  accidentally  making  too  large  a  perforation  through 
the  floor,  an  additional  piece  of  the  metal  of  smaller  dimensions  mav  be 
properly  perforated  and  burnished  down  over  the  surface  before  removing 


148 

and  investing  the  cap  and  dowel,  and  subsequently  attached  at  the  time  of 
soldering. 

The  cap  should  be  cleaned  in  the  acid  bath  after  removing  from  the 
investment,  and  then  adjusted  to  position  on  the  root  and  the  bite  and 
impression  taken. 

In  the  construction  of  anterior  crowns,  the  tak- 

"BltC."  ing  of  a  "bite"  usually  becomes  necessary  only  when 

some  abnormality  of  occlusion,  or  irregularity  of  the 

opposing  teeth,  presents.     Otherwise  the  lingual  contour  of  the  adjacent 

teeth  as  represented  in  the  model  will  indicate  the  outlines  to  be  followed 

by  this  portion  of  the  crown. 

When  a  bite  is  necessary,  it  should  be  taken  in  wax,  preceding  the 
impression,  and  should  be  secured  in  accordance  with  the  requirements  of 
the  impression,  and  in  the  manner  previously  outlined. 

The  impression  should  then  be  taken  in  plaster 

Tmpression.  for  the  reasons  already  stated,  and  should  always  in- 

clude teeth  on  each  side  of  the  one  being  crowned, 
and  the  corresponding  tooth,  when  present. 

If  the  projecting  surplus  end  of  the  dowel  is  slightly  bent,  the  cap 
will  be  removed  with  the  impression,  but  in  the  event  of  its  remaining  upon 
the  root,  it  should  be  detached  and  adjusted  accurately  to  position,  and 
securely  sustained,  if  necessary,  with  a  little  melted  wax.  The  interior  of 
the  cap  and  the  surface  of  the  dovel  should  now  he  covered  with  a  slight 
aim  of  melted  wax  to  facilitate  and  admit  of  its  ready  removal  from  the 
model,  and  the  impression  then  varnished  and  filled. 

When  the  model  has  been  obtained,  the  bite,  if  one  has  been  taken, 
should  be  adjusted,  and  the  case  mounted  upon  the  articulator.  The  cap 
may  now  be  easily  detached  by  grasping  the  end  of  the  dowel  with  pliers, 
and  the  wax  then  removed  from  its  interior,  which  will  admit  of  its  ready 
and  accurate  readjustment,  thus  facilitating  the  investment  of  the  crown, 
and  permitting  the  preservation  of  the  model. 

In  cases  where  the  remaining  natural  teeth  are  quite  loose,  or  support 
artificial  crowns  of  doubtful  stability,  the  use  of  small  particles  of  wax 
packed  into  the  interproximal  spaces,  and  into  all  undercuts,  will  be  found 
to  be  advantageous  to  the  removal  of  the  impression,  and  to  the  comfort 
of  the  patient. 

Jfdaptation  of  Tdcings. 

Previous  to  the  selection  and  adaptation  of  the  facing,  the  surplus  end 
of  the  dowel  should  be  cut  off  with  excising  forceps  or  cutting  pliers,  leav- 
ing it  as  long  as  possible  so  as  not  to  interfere  with  the  adjustment  of  the 
facing  to  its  proper  position. 


149 

As  the  floor  is  very  thin,  however,  some  httle  surplus  should  always 
be  allowed  to  remain,  in  order  to  add  strength  to  the  attachment  of  the 
dowel. 

A  long  pin  facing  should  now  be  selected  and  ground  to  a  perfect 
joint  with  the  cap,  along  its  cervical  curvature,  and  then  to  meet  the 
requirements  of  length,  contact  and  characteristics. 

When  this  required  and  proper  adaptation  of  the 

Cerpical  €nd.         cervical  end,  to  the  cap,  is  secured,  the  inner  surface 
of  the  facing  should  be  thinned  down  somewhat  until 
sufificient  space  exists  to  afford  opportunity  for  securing  a  close   joint 
between  the  backing  and  the  cap,  with  solder. 


Ficj.128. 


The  incisal  or  occlusal  end  should  now  be  bev- 
Tncisal  or  eled  about  half-way  to  the  pins,  in  order  that  it  may 

Occlusal  €nd.         present  a  smooth,  sharp  angle,  instead  of  the  usual 
rounding  edge.      (Fig.  *28.)      This  becomes  neces- 
sary as  a  means  of  affording  a  definite  edge  to  which  the  backing  may  be 
subsequently  finished. 


Ficj.  129. 


The  use  of  the  clamp  designed  by  Dr.  A.  Brom  Allen,  of  Chicago 
(Fig.  129)  will  be  found  convenient  for  holding  porcelain  facings  while 
grinding. 

Backiiid  or  Tacittg. 

The  backing  of  porcelain  facings  becomes  necessary  in  metal  work 
as  a  means  of  supporting  them,  by  affording  a  surface  which  will  atlmit  of 
their  subsequent  attachment  with  solder. 

The  requirements  in  this  connection  embrace  tivo  essential  features : 
First,  the  backing  must  be  closely  adapted  to  the  porcelain,  and,  second,  it 
must  be  sufficiently  strong,  rigid  and  unyielding,  to  protect  the  porcelain 
from  the  strain  of  mastication 

While  numerous  methods  are  employed,  the  following  will  be  found 


ISO 

to  be  productive  of  the  most  certain  and  accurate  results,  though  possibly 
somewhat  less  expeditious  than  the  more  simple  methods  usually  observed. 

Pure  gold,  about  34  gauge,  cut  somewhat  larger  than  the  facing,  and 
to  extend  from  cervical  to  incisal  or  occlusal  edges,  should  be  perforated 
for  the  ready  reception  of  the  pins,  annealed,  and  carefully  burnished  to 
a  perfect  adaptation. 

As  it  is  desirable  that  the  perforations  should  be  properly  placed,  so 
as  to  admit  of  the  free  and  easy  adjustment  of  the  porcelain  to  position, 
and  to  preclude  any  strain  upon  the  pins  in  adapting  the  backing,  it  should 
first  be  observed  that  the  pins  are  straight  and  parallel  with  each  other,  and 
that  this  surface  of  the  porcelain  is  clean  and  free  of  wax. 

As  a  means  of  ascertaining  the  exact  position  of 

Jidaptation.  the  pins,  the  gold  should  be  laid  on  a  smooth  surface 

and  the    facing  placed    over  it,  pins    downward,  and 

sufficient  pressure  applied  with  the  thumb  to  make  a  slight  indentation. 


The  perforations  may  now  be  made  with  a  punch  designed  for  the 
purpose,  or  with  a  sharp  pointed  instrument  of  proper  size.  The  use  of 
the  latter  possesses  the  advantage  of  throwing  up  a  small  furrow  of 
metal  around  the  holes,  and  is  preferable. 

Or,  a  very  accurate  adaptation  may  be  made  by 
C1)C  Btmt  employing  the  "Acme  Backing  Forceps,"  which  are 

Backing  Torccps.  so  constructed   as   to  both  perforate   and   adapt  the 

backing  directly  to  the  facing. 
After  annealing  and  burnishing  the  gold  to  a  perfect  adaptation,  the 
surplus  should  be  trimmed  away  to  closely  follow  the  porcelain  on  all  sur- 
faces except  the  incisal  or  occlusal,  where  a  slight  projecting  edge  should 
be  allowed  to  remain. 

While  the  requirement  of  adaptation  has  now  been  complied  with  in 
the  best  and  easiest  possible  manner,  that  of  strength  is  yet  to  be  observed. 

As  the  strain  upon  a  facing  is  generally  applied 
KMnforccment.  directly  upon  the  end,  and  then  diverted  to  the  point 

of  resistance  afforded  by  the  pins,  it  is  necessary  that 
a  uniform  re-enforcement  extending  over  this  area  should  be  made. 

To  best  obtain  this,  anfl  thus  combine  the  requirements  of  adaptation 
and  strength,  a  second  piece  of  gold,  preferably  about  22  karat,  29  or  30 


151 

gauge,  should  be  perforated,  burnished  to  place,  and  trimmed  to  extend 
from  the  pins  to  the  incisal  or  occlusal  end  only,  with  a  corresponding  sur- 
plus at  the  latter  point. 

The  two  backings  should  now  be  adjusted  to  po 
Soldering.  sition  on  the  facing  and  reburnished,  then  removed, 

placed  together  with  the  holes  approximating  each 
other,  which  is  facilitated  by  the  furrow  of  metal  produced  by  being 
punched  with  a  sharp  instrument,  and  then,  attached  with  20  or  18  karat 
solder.  Small  pieces  of  the  latter  should  be  consecutively  applied  to  the 
joint  between  the  two,  presenting  toward  the  cervical  end,  until  the  inter- 
vening space  is  completely  filled,  which  may  be  easily  and  quickly  accom- 
plished by  grasping  the  backings  with  the  soldering  pliers,  as  indicated  in 
Fig.  130,  the  use  of  which  securely  sustains  their  relation,  and  precludes 
any  distortion  of  shape. 

The  use  of  an  excess  of  flux  should  be  avoided,  and  care  must  be  ex- 
ercised to  prevent  the  solder  from  filling  the  perforations,  or  flowino- 
through  to  the  under  side  of  the  backing,  and  thus  destroying  the  adapta- 
tion. The  latter  may  be  easily  avoided  by  coating  this  surface  with  a  solu- 
tion of  whiting,  but  is  usually  prevented  by  the  upturned  edges  surround- 


FicjJSI. 

ing  the  perforations,  which  also  generally  precludes  their  filling  up  with 
solder.  The  use  of  small  pieces  of  graphite  from  an  ordinary  lead  pencil 
trimmed  to  snugly  fit,  and  to  project  slightly  from  each  side,  will  alsr 
overcome  any  such  tendency. 

When  the  soldering  has  been  completed,  the  backing  should  oe 
cleaned  in  acid,  adjusted  to  position  on  the  facing  (Fig.  131,  A),  and  se- 
curely retained  by  bending  the  pins  down  close  upon  it,  as  indicated  in 
Fig.  131,  B.  Care  must  be  exercised  in  bending  the  pins  to  catch  them 
with  pliers  at  the  extreme  end,  in  order  to  avoid  any  stress  or  tension 
which  might  result  in  immediate  or  subsequent  fracture  of  the  porcelain. 

In  finishing,  the  gold  should  be  trimmed  down  to 

Tinishing.  close  contact  with  the  porcelain  around  all  surfaces. 

This  should  be  started  with  a  fine  file,  alwavs  carrv- 

ing  it  toward  the  porcelain;  and  completed  with  disks,  to  insure  the  vz- 


152 

moval  of  all  overhanging  edges,  the  presence  of  which  will  invariably 
cause  fractures  of  the  porcelam  along  the  edges,  due  to  the  impingement 
afforded  by  the  shrinkage  and  contraction  of  the  metal  after  soldering. 

In  trimming  away  the  surplus  from  the  incisal  or  occlusal  portion  the 
file  should  be  held  on  a  parallel  line  with  the  labial  or  buccal  aspect  of  the 
facing.  This  leaves  the  backing  its  full  thickness  along  this  edge,  the  vul- 
nerable point,  when  it  may  be  afterward  rounded  nicely  until  practically 
invisible,  and  yet  always  remain  sufficiently  long  and  strong  to  afford 
ample  protection  to  the  porcelain.  (Fig.  131,  C.)  Much  of  the  artistic 
effect  of  the  finished  crown  will  depend  upon  obtaining  and  preserving 
a  perfect  joint  between  the  neck  of  the  facing  and  the  cap,  and  while  it 
is  the  usual  practice  to  grind  this  portion  of  the  facing  thin,  and  allow 
the  backing  to  extend  entirely  over  it,  forming  a  joint  with  the  cap  which 
is  subsequently  filled  with  solder,  the  best  results  may  be  secured  by 
filing  or  grinding  away  this  edge  of  the  backing  until  the  edge  of  the 
facing  may  be  placed  in  direct  contact  zvith  the  cap. 

This  admits  of  bringing  the  facing  into  closer  proximity  with  the 
gum  and  of  securing  a  better  and  more  perfect  joint  between  backing  and 
cap,  because  of  the  difficulty  and  uncertainty  usually  experienced  in 
successfully  filling  this  space  with  solder. 

The  use  of  the  clamp  previously  mentioned  may  also  be  found  ser- 
viceable as  a  means  of  holding  the  facing  while  finishing  the  backing. 

As  the  double  backing  may  seem  unnecessarily 
Uariation  in  method,    difficult  or  circuitous,  various  other  methods  are  em- 
ployed in  preference,  but  probably  with  results  less 
certain  and  accurate. 

The  re-enforcement  of  the  single  pure  gold  backing  may  be  done  with 
a  lower  grade  of  gold,  or  with  solder  alone,  either  preceding  its  final 
adaptation  to  the  porcelain,  or  at  the  time  of  soldering  the  facing  to  the 
cap.  There  is  no  objection  to  this  procedure  if  adequate  re-enforcement 
is  secured,  but  as  gold  or  solder  in  fusing  flows  to  a  thin  edge,  the  edges  of 
the  backing  and  particularly  the  incisal  or  occlusal,  where  strength  is  de- 
manded, are  quite  naturally  the  thinnest,  and  consequently  the  weakest 
portions. 

This  may  be  overcome  somewhat  by  allowing  a  slight  surplus  to  ex- 
lend  beyond  the  porcelain,  especially  upon  the  incisal  or  occlusal  end,  until 
after  re-enforcing,  and  then  adjusting  to  position  on  the  facing,  and  se- 
curely attaching  and  finishing,  as  indicated.  In  no  event,  however,  when 
a  single  pure  gold  backing  is  used,  is  it  advisable  to  defer  the  re-enforce- 
ment until  the  final  soldering  of  the  crown. 

Where  a  single  backing  seems  indicated  or  desirable,  it  should  be 
made  of  22  karat  gold,  about  28  or  30  gauge,  but  as  the  burnishing  to  the 


153 

porcelain  is  thus  made  more  difficult,  the  additional  stiffness  and  strength 
is  usually  obtained  at  the  expense  of  the  adaptation. 

The  adaptation  of  heavy  single  backings  may  be  materially  improved 
by  swaging.  For  this  purpose  a  mould  of  the  lingual  surface  of  the  porce- 
lain should  be  secured  in  mouldine,  and  fusible  alloy  dies  obtained,  and 
dies  made  of  ordinary  sealing  wax,  or  hard  modeling  compound  are  also 
sometimes  used,  or,  the  facing  itself  may  be  imbedded  in  either  of  these,  the 
backings  perforated,  and  then  swaged  to  them  with  a  soft  rubber  nlunger. 

As  porcelain  facings  are  more  or  less  transparent, 
U$t  Of  Platinum.       the  presence  of  a  gold  backing  is  frequently  objec- 
tionable in  the  blue  and  lighter  shades,  because  of  the 
yellowish  cast  imparted  to  them ;  hence  the  placing  of  a  surface  of  plati- 
num next  to  the  facing  is  sometimes  indicated  as  a  means  of  preserving 
the  original  color,  or  of  effecting  the  least,  or  most  desirable,  change  in  it. 
For  this  purpose,  platinized  gold  is  employed,  and  possesses  the  ad- 
vantage of  affording  a  surface  of  either  gold  or  platinum,  as  the  case  may 
require.     A  more  convenient  method,  however,  is  to  back  up  the  facing  in 


Fi(j.  132. 

tl;e  usual  manner,  and  then  insert  a  piece  of  platinum  foil  (i-iooo)  over 
the  desired  area  between  facing  and  backing,  just  pre.vious  to  permanently 
attaching  them  by  bending  the  pins,  and  finishing  the  backing  to  its  proper 
adaptation  ;  by  which  means  equally  good  and  perhaps  quicker  results  may 
be  obtained. 

When  the  adaptation  and  finishing  of  the  back- 
Tnvesting.  ing  have   been  completed,  the    facing  should   be  ad- 

justed to  position  on  the  cap,  and  the  proper  relation 
sustained  with  wax.  The  crown  should  now  be  removed  from  the  model, 
and  the  joint  between  cap  and  backing  well  filled  with  melted  wax.  This 
keeps  it  clean  and  free  of  investment  material,  which  is  essential  to 
securing  a  smooth  fiush  joint  with  solder,  and  the  latter  may  be  facilitated 
by  using  Huxcd  wax. 

Investment  material  should  now  be  mixed  to  a  thin  plastic  consist- 
ency, and  a  sufficient  quantity  poured  upon  the  surface  of  a  clean  piece  of 
paper.     The  interior  of  the  cap  should  first  be  thoroughly  filled,  and  the 


154 

crown  then  gently  forced  into  the  investment,  until  only  the  wax  remains 
exposed.  After  hardening,  the  surplus  should  be  trimmed  to  the  outlines 
mdicated  in  Fig.  26,  and  the  wax  carefully  removed  with  a  small  pointed 
knife-blade,  being  particular  not  to  loosen  the  facing  in  its  matrix. 

In  those  cases  where  the  backing  has  been  allowed  to  extend  entirely 
through  between  facing  and  cap  some  difficulty  is  occasionally  experienced 
in  getting  the  solder  to  flow  nicely  into  the  joint,  and  while  this  may  usu- 
ally be  accomplished  by  properly  fluxing  and  heating  the  case  before  at- 
tempting to  solder,  if  the  proximity  of  the  surfaces  is  very  close  the  same 
may  be  greatly  facilitated  by  placing  a  small  projecting  bead  of  wax 
around  the  immediate  outside  of  the  joint,  before  investing  (Fig.  132,  A). 
When  melted  and  subsequently  absorbed  and  burned  out,  this  leaves  a 
small  space  into  which  the  heat  becomes  concentrated,  during  the  process 
of  soldering,  and  this  aids  materiall}-  in  drawing  the  solder  toward  that 
point. 

The  cutting  of  a  small  opening  through  the  under  surface  of  the  in- 
vestment until  the  joint  is  exposed  is  also  recommended  for  this  purpose, 
and  the  same  may  be  easily  obtained  by  extending  the  bead  of  wax  previ- 
ously mentioned  until  it  is  of  proportions  sufficient  to  leave  such  an  open- 
ing after  its  removal.     (Fig.  132,  B.) 

In  cases  where  two  or  more  individual  crowns,  approximating  each 
other,  are  being  constructed  at  the  same  time,  they  should  always  be  in- 
vested separately,  as  it  is  often  quite  difficult  to  solder  them,  when  con- 
tained in  the  same  investment,  without  attaching  them  together. 

Previous  to  heating  the  case  for  the  purpose  of 
SOldCfing.  final   soldering,   and   after   the   investment  has  been 

properly  trimmed,  and  all  debris  removed,  liquid  flux 
should  be  applied  to  the  surface  of  cap  and  backing,  and  worked  well  down 
into  the  joint.  If  the  latter  is  done  after  the  case  is  heated,  or  if  powdered 
flux  is  used,  its  penetration  to  the  full  depth  of  the  joint  is  made  more 
doubtful. 

The  case  should  now  be  placed  over  the  flame  and  gradually  heated 
until  red,  when  medium-sized  pieces  of  solder,  previously  fluxed,  should 
be  separately  and  consecutively  applied,  and  fused,  until  the  joint  is  first 
filled,  and  the  desired  contour  obtains.  If  the  case  is  properly  heated,  this 
can  be  easily  and  readily  accomplished  with  a  small  pointed  flame  from  the 
blowpipe. 

When  the  soldering  has  been  completed,  the  crown  should  be  allowed 
to  cool  slowly  by  gradually  diminishing  the  size  of  the  flame  under  it,  until 
it  may  be  turned  off  entirely.  Many  prefer  to  place  the  work  in  a  cooling 
oven,  or  to  submerge  it  into  dry  plaster  until  cold,  but  either  procedure  is 
entirely  unnecessary. 


155 

After  cooling  sufficiently,  it  should  be  removed 
TinUbing.  from  the    investment,  treated    to  the  acid    bath,  and 

then  finished  with  stones  and  disks  in  the  engine,  and 
subsequently  polished  on  the  lathe,  when  it  is  ready  for  mounting. 

Jlpplication  of  Partial  Bands. 

The  application  of  a  partial  band  encircling  only  the  approximal  and 
lingual  surfaces  of  the  root  is  advocated  and  employed  more  or  less 
frequently  in  the  construction  of  dowel  crowns,  as  a  means  of  avoiding 
the  presence  of  a  labial  band,  from  an  esthetic  standpoint,  and  of  pre- 
cluding its  possible  irritating  influence,  as  a  prophylactic  measure. 

A  consideration  of  the  comparative  advantages 

Comparative  leads   to  the  conclusion  that,  while  a  band  encom- 

Jfdvantaaes.  passing    the    entire    circumference    doubtless    adds 

greater  stability  to  the  attachment  of  the  crown, 
affords  a  more  perfectly  hermetical  sealing  of  the  end  of  the  root,  over- 
comes the  possibility  of  fracture,  may  be  made  practically  invisible,  and 
will  not  necessarily  prove  a  source  of  irritation,  providing  that  it  £fs,  the 
partial  band,  if  well  adapted  to  the  lingual  and  approximal  surfaces, 
fortifies  the  attachment  against  stress  in  the  direction  from  which  stress 
is  exerted,  makes  it  possible  to  bring  the  facing  into  absolute  and  direct 
contact  with  the  tissue,  and  precludes  any  irritation  at  this  point,  or  the 
conspicuous  and  objectionable  appearance  of  the  band  in  the  event  of 
subsequent  recession  of  the  tissue. 

The  indications  for  the  application  of  this  mode 

Indications,  of  construction  are  more  or  less  general,  but  depend 

much  upon  personal  experience  and  preference,  com- 
bined with  a  careful  observation  of  the  particular  requirements  of  the 
case  under  treatment. 

Of  special  indications,  the  most  favorable  are  those  cases  where  the 
root  is  sufficiently  strong  to  insure  permanent  support  to  a  crown ;  or 
where  the  labial  portion  of  the  root  may  have  been  destroyed  to  the 
border  of  the  alveolus ;  where  the  extreme  shortness  of  the  crown,  or 
the  thinness  and  transparency  of  the  tissue  surrounding  the  root,  would 
likely  show  the  presence  of  the  band ;  where  recession  of  the  gums  has 
exposed  the  labial  portion  of  the  root ;  and  where  pathological  conditions 
already  exist,  or  the  tissue  may  seem  to  be  particularly  susceptible 
to  any  possible  irritating  influence. 

Procedure. 

While  several  methods  of  securing  the  desired  adaptation  are  em 
ployed,  the  most  positive  and  accurate  results  may  be  obtained  by  fol- 


156 

lowing  the  same  detail  of  procedure  indicated  for  a  circular  band,  up  to 
and  including  its  fitting,  shaping  and  trimming,  as  previously  outlined. 

When  the  band  has  been  thus  fitted  and  trimmed,  a  floor  of  platinum 
or  pure  gold,  about  34  gauge,  should  be  first  simply  attached  to  the  lingual 
surface  by  the  partial  fusion  of  a  small  piece  of  solder.  The  floor  should 
then  be  adapted  closely  to  the  entire  edge  of  the  band,  and  a  precaution- 
ary measure  observed  to  prevent  their  union  with  solder  along  that  edge 
of  the  band  which  is  to  be  subsequently  cut  away.  To  accomplish  this, 
such  portion  of  the  joint  between  floor  and  band  should  be  filled  with  a 
solution  of  whiting,  or  occupied  by  a  thin  piece  of  mica  (Fig.  133  A) 
and  the  soldering  completed  around  the  approximal  and  lingual  sur- 
faces. 

The  surplus  floor  metal  should  be  trimmed  off  on  a  line  with  the 
band,  and  the  labial  portion  of  the  latter  cut  away  to  the  desired  point 
with  curved  shears,  always  leaving  the  edge  nicely  rounded.  (Fig. 
133  B.) 


When  the  trimming  and  finishing  of  the  cap  have  been  completed,  it 
should  be  adjusted  to  position  on  the  root,  and  the  projecting  labial  portion 
of  the  floor  burnished  to  a  close  adaptation  to  the  surface  and  to  the  per- 
ipheral outline. 

The  dowel  should  be  fitted  and  subsequently  sold£red,  and  the  impres- 
sion then  taken,  and  the  crown  completed  as  already  outlined.       (Fig. 

133  C.) 

Another   method    of   constructing   this    type   of 

CfcC  Sanger  Crown.        crown  has  been  devised  by  Dr.  R.  M.  Sanger.    In  this 

procedure     both     the     partial     band     and     base     of 

crown  are  made  of  one  piece  of  metal,  and  formed  in  such  manner  as  to 

admit  of  easy  and  accurate  adjustment  by  means  of  pliers  of  special  design. 

Jlpplicdtion  of  Riocted  Tacings. 

Because  of  the  apparent  dread  exhibited  by  those  of  limited  con- 
fidence or  experience,  toward  the  process  of  soldering  anything  necessarily 
involving  porcelain,  for  fear  of  checking  it,  and  of  its  possible  change  of 
color  as  a  result  of  the  application  of  heat,  a  method  has  been  devised 


157 

whereby  the  occurrence  of  either  or  both  of  these  objectionable  features 
might  be  entirely  and  positively  eliminated. 

The  process  defers  the  permanent  attachment  of  the  facing  to  the 
backing  until  after  the  construction  and  assemblage  of  all  the  metal  parts 
of  the  crown,  after  which  it  is  then  securely  anchored  by  riveting  the  pins. 

While  there  are  probably  no  particular  objections  to  this  method, 
except  that  the  facing  is  held  less  rigidly,  there  are  no  special  advantages 
apparent  because  of  the  limited  possibilities  of  checking  facings,  which 
have  been  previously  mentioned  in  connection  with  "Soldering,"  and  of 
the  fallacy  of  a  probable  change  in  color  resulting  from  the  heat  of 
soldering. 

That  any  perceptible  change  of  color  is  due  mainly  to  the  presence 
of  the  backing,  and  not  to  the  heat,  is  proven  in  porcelain  work,  where, 
when  necessarily  subjected  to  a  very  much  higher  degree,  it  is  even  then 
the  rare  and  exceptional  occurrence;   and  it  would  also  seem  that  the 


a 

Ficj.134- 

impact  and  vibration  produced  by  subsequently  riveting  the  projecting 
ends  of  the  pins  down  close  upon  the  backing  would  be  equally  as  "haz- 
ardous" a  process  as  that  of  soldering. 

Procedure. 

In  the  construction  of  crowns  by  this  method  the  same  general 
details  as  previously  outlined  are  observed  up  to  and  including  the  adap- 
tation of  the  backing. 

When  this  has  been  accomplished  it  should  be  adjusted  to  position  on 
the  facing  and  finished  down  as  desired,  in  the  usual  manner,  c.vccpt 
that  the  pins  are  not  bent  to  sustain  the  relation  of  the  two  during  the 
process. 

Facing  and  backing  together  are  placed  in  proper  relation  io  the 
cap  and  sealed  with  a  small  quantity  of  hard  or  adhesive  wax  in  sucii 
manner  as  to  securely  attach  the  backing,  but  to  allow  the  projecting  ends 
of  the  pins  to  remain  freely  exposed.     (Fig.  134  A.) 


158 

The  crown  should  now  be  gently  removed  from  the  model  and  the 
facing  carefully  detached  from  the  backing. 

Small  pieces  of  graphite  trimmed  from  a  lead  pencil  are  then  closely 
fitted  into  the  holes  in  the  backing  and  allowed  to  project  far  enough  on 
each  side  to  be  securely  held  by  the  investment,  and  to  admit  of  properly 
forming  the  lingual  contour  with  solder  without  being  covered  over. 
(Fig.  134  B.) 

The  remaining  incisal  portion  of  the  lingual  surface  of  the  backing 
should  be  covered  with  wax  to  keep  it  clean,  and  the  crown  invested. 
Upon  the  subsequent  removal  of  the  wax  the  parts  should  be  freely 
exposed,  fluxed,  heated  and  soldered  as  usual,  being  careful  to  note  that 
the  ends  of  the  graphite  pins  are  not  covered,  and  that  the  solder  does  not 
penetrate  to  the  under  surface  of  the  backing,  which  is  prevented  by 
painting  around  the  pins  with  whiting. 


F/cfJ35, 


When  the  soldering  has  been  completed,  the  graphite  may  be  broken 
off  even  with  the  surfaces  and  removed  from  the  holes  by  the  use  of  a 
sharp  pointed  instrument  or  bur  of  the  same  diameter. 

The  facing  should  now  be  adjusted  to  position  and  the  lingual  surface 
of  the  crown  trimmed  to  allow  a  free  exposure  of  the  projecting  ends  of 
the  pins.  The  holes  should  then  be  slightly  countersunk  with  a  round  bur, 
the  crown  roughly  finished  with  stones  and  disks,  and  the  facing  finally 
adjusted  for  riveting. 

As  a  means  of  facilitating  the  process  of  riveting, 
Riveting.  and  of  lessening  the  liability  of  fracturing  the  porce- 

lain, the  riveting  forceps  designed  by  Dr.  Frank  A. 
Brewer,  Sr.,  may  be  used  to  advantage ;  or  the  crown  may  be  invested, 
facing  downward,  in  a  base  of  plaster  about  an  inch  in  depth  (Fig.  135) 
and  the  riveting  hammer  used.     In  the  latter  method  the  projecting  ends 


159 

of  the  pins  are  flattened  down  over  the  backing  separately, 
with  moderate  and  well-directed  blows  from  a  small  riveting  hammer.  If 
the  crown  is  properly  invested,  with  a  sufficient  depth  of  plaster  beneath 
and  supporting-  the  facing,  and  the  whole  rests  upon  a  firm  seating,  this 
may  be  done  without  danger  of  fracturing  the  porcelain.  The  riveted  ends 
are  then  smoothed  down  with  disks  and  the  crown  finished  and  polished, 
burnishing  the  metal  up  close  to  the  porcelain  around  ihe  edges. 

Jlpplicdtion  of  DetacDable  ana  KcplaccaDk  Tacings. 

The  not  infrecjuent  presentation  of  broken  facings  resulting  after  the 
permanent  mounting  of  the  crown,  combined  with  the  more  or  less  diffi- 
cult operation  of  replacing  them  in  a  secure  and  artistic  manner,  has 
resulted  in  the  introduction  of  various  means  for  overcoming  the  former 
and  simplifying  the  latter. 

Several  varieties  of  detachable  and  replaceable  facings  are  designed 
for  this  purpose,  and  are  applicable  to  the  construction  of  dowel  crowns 
as  well  as  bridgework,  though  perhaps  more  generally  so  to  the  latter. 

While,  as  a  usual  thing,  it  must  be  granted  that  the  subsequent  frac- 
turing of  a  porcelain  facing  is  due  to  one  of  two  causes,  i.  e.,  either  faulty 
adaptation  of  the  backing,  wherein  it  affords  insufficient  strength  or 
inadequate  protection,  or  a  total  disregard  of  the  requirements  of  occlusion, 
the  use  of  a  style  which  is  easily  replaceable  is  doubtless  an  advantage  in 
some  instances. 

When  these  common  faults  in  regard  to  backing  the  facings  are  com- 
bined with  the  severe  strain  to  which  the  porcelain  is  often  subjected  in 
some  conditions  of  occlusion,  and  the  perhaps  unnecessarily  rough  usage 
sometimes  unconsciously  accorded  them,  any  practical  means  of  facilitating 
repair  in  the  event  of  accident  is  materially  useful. 

The  advantages  claimed  by  the  advocates  of  this 
JIdvantagCS  Claimed,  style  of  facing  are:  First,  that  the  porcelain  is  not 
subjected  to  the  heat  of  soldering;  second:  facings 
may  be  more  easily  replaced  in  the  event  of  becoming  fractured ;  third : 
the  probability  of  becoming  fractured  from  usage  is  greatly  diminshed 
because  the  facing  is  not  so  rigidly  attached  to  the  metal  backing;  fourth, 
the  color  is  not  changed. 

The  first  point  made  is  practically  the  zccakcst, 
Jidpantages  Considered,  because  the  fracturing  of  a  facing  during  the  process 
of  soldering  it  to  any  kind  of  an  attachment  is  inex- 
cusable, and  can  be  invariably  attributed  to  either  a  lack  of  skill  or  a 
neglect  of  detail. 

The  sccor.d  must  be  regarded  as  problematical,  at  least  in  the  manner 


i6o 

'n  which  these  facings  are  ordinarily  used,  for  the  reason  that  it  is  often 
impossible  to  properly  adapt  any  style  or  kind  of  facing  to  the  individual 
case  without  considerable  grinding. 

For  this  reason  also  the  subsequent  replacement  of  even  an  exact 
duplicate  of  the  same  mould  would  occasion  the  necessity  for  grinding 
the  latter  to  an  accurate  fit  and  adaptation  with  the  stationary  backing, 
and  to  meet  the  esthetic  requirements,  which,  irrespective  of  the  manner 
of  attachment,  is  not  usually  an  easy  or  simple  procedure. 

The  third  feature  presents  the  most  practical  and  plausible  advantage, 
because  a  porcelain  facing  supported  by  mechanical  means  supplemented 
with  an  intervening  medium  such  as  gutta  percha,  or  even  cement,  which 
affords  a  somewhat  cushion-like  effect,  will  withstand  greater  stress  than 
one  held  firm  and  rigid.  Hence  fracture  is,  of  course,  less  likely  to  occur 
since  the  facing  will  yield  slightly  to  stress  before  breaking. 

The  fourth  point  of  advantage  is  doubtful,  for  the  reason  that  any 
change  of  color  is  usually  due  to  excessive  heat,  or  the  presence  of  the 
backing,  as  has  been  previously  mentioned. 

If  the  highest  advantages  are  to  be  obtained  in 

Advantages  the  use  of  this  style  of  porcelain  facing,  the  adoption 

Obtainable.  of  a  method  suggested  and  practiced  by  Dr.  F.  T. 

Van  Woert  and  others  will  be  found  most  practicable. 

This  consists  of  properly  grinding  and  adapting  two  or  more  facings 
of  the  same  color  and  mould,  as  the  conditions  of  occlusion  may  seem  to 
indicate,  for  each  case  at  the  time  of  construction.  Those  not  used  in 
completing  the  crown  are  then  placed  in  small  boxes  or  other  convenient 
receptacles  and  labeled  with  the  patient's  name.  In  case  of  breakage  occur- 
ring at  any  subsequent  time,  a  duplicate  requiring  no  fitting  or  grinding, 
and  which  may  be  readily  adjusted  to  position,  is  conveniently  obtainable. 

While  such  a  procedure  may  involve  considerably  more  work  at  the 
time,  much  may  often  be  saved  in  the  long  run,  and  particularly  in  difficult 
cases,  where  much  grinding  is  necessary. 

Uarious  De$idn$. 

Of  the  various  designs  of  detachable  facings  now  procurable,  the 
demand  has  seemingly  not  justified  the  adoption  of  any  one  special  make 
in  preference  to  the  others,  nor  their  extensive  manufacture  in  any  great 
variety  of  moulds  and  colors. 

The  design  of  removable  or  detachable   facing 

mason's  TaciBfl.       devised  by  Dr.  W.  L.  Mason,  of  Red  Bank,  N.  Y.,  is 

probably  the  most  extensively  used.     It  consists  of 

a  heavy  gold  backing  having  a  triangular  slot  through  the  center  and  a 

tacing  with  a  projecting  corresponding  triangular  platinum  bar  extending 


i6i 

longiturlinally,  through  the  center,  which  readily  telescopes  into  the  slol; 
in  the  backing-.     (Fig.  136  A.) 

These  facings  are  obtainable  in  a  fairly  good  variety  of  moulds  and 
colors,  and  the  principle  of  attachment  is  secure  and  admits  of  easy  adjust- 
ment. The  objectionable  features  lie  in  the  seemingly  excessive  proportion 
of  platinum  baked  in  the  porcelain,  which  doubtless  weakens  the  latter  by 
dividing  it  through  the  center,  and  in  the  necessary  thickness  at  the  incisal 
or  occlusal  end. 

In  the  application  of  this  style  of  facing  the  cap 

Application.  should  be  completed  as  prescribed,  and  the  models 

obtained  and  mounted  upon  the  articulator.  After  the 
selection  of  the  facing  its  backing  should  be  adjusted  and  two  facings,  in 
situ,  ground  to  fit  the  cap  and  to  conform  to  the  usual  requirements.  When 
the  desired  adaptation  is  secured  the  relation  to  the  cap  should  be  sustained 
by  attaching  the  backing  to  it  with  hard  or  adhesive  wax,  and  the  facing 
then  detached,  which  is  facilitated  by  a  projecting  end  of  the  platinum  bar 


Ficj.iae, 


at  the  incisal  or  occlusal  edge.  Care  should  be  exercised  in  securing  a 
close  relation  between  the  backing  and  the  cap,  in  order  that  any  penetra- 
tion of  solder  through  the  joint  may  be  precluded,  and  this  may  be  further 
prevented  by  filling  the  slot  and  coating  backing  with  wdiiting.  The 
metal  parts  should  now  be  invested  and  soldered,  with  due  attention  to 
the  desired  lingual  contour. 

After  soldering,  the  crown  should  be  finished  (Fig.  136  B),  and  the 
facing  then  adjusted  to  position.  The  projecting  end  of  the  platinum  bar 
should  now  be  cut  off  and  the  facing  attached  to  the  backing  with  a  thick 
solution  of  gutta  percha  in  chloroform,  after  which  the  edge  should 
be  finished  up  close  to  the  porcelain,  and  the  crown  mounted.  Or,  if 
desirable,  the  setting  of  the  facing  may  be  made  after  the  crown  has  been 
attached  to  the  root  and  cement  is  also  some  times  used. 

Another  design   of  removable   facing  has   been 
Roach's  facing,       devised  by  Dr.  F.  E.  Roach,  of  Chicago,  and  for  sim- 
plicity and  strength,  combined  with  accuracy  of  adap- 
tation, and  ready  application  to  either  individual  crowns  or  dummies  tor 


l62 

bridgework,  it  presents  many  favorable  features.  The  design  consists  of 
a  facing  with  a  dovetail  lug  extending  lingually,  which  is  stamped  of  one 
piece  of  iridio-platinum  (Fig.  137  A),  and  a  backing  with  a  slotted 
diaphragm  into  which  the  lug  fits  accurately  (Fig.  137  B). 

The  lug  is  placed  vertically  in  the  body  of  the  facing,  and,  being 
entirely  surrounded  by  porcelain,  affords  to  the  latter  a  maximum  degree 
of  strength,  and  is  set  at  an  angle  which  admits  of  easy  adjustment  to  the 
backing. 

The  backing  is  composed  of  two  parts  securely  united.  The  outer 
portion,  which  is  of  pure  gold,  about  34  gauge,  is  intended  to  facilitate 
ready  and  accurate  adaptation  to  the  porcelain,  after  grinding;  and  the 
central  portion,  which  affords  the  means  of  attachment,  is  in  the  form 
of  a  slotted  diaphragm,  made  of  26  gauge  clasp  metal. 

While  the  principle  of  attachment  is  good  and  secure,  the  pliability 
of  the  outer  backing  insures  a  close  adaptation  to  the  surface  and  edges 
of  the  porcelain;  the  gingival  extension  admits  of  a  close  joint  between 


FicjJ37. 


facing  and  cap,  and  no  excess  metal  exists  at  the  incisal  end  to  offer 
obstruction  to  the  occlusion,  the  merits  and  demerits  of  these  facings, 
and  their  possibilities,  range  of  usefulness  and  gejieral  application  are 
at  present  uncertain,  because  of  the  limited  supply  and  selection  procurable. 

After  constructing  the  cap  and  obtaining  models, 

Hpplication.  the  facing  should  be  selected  and  ground  to  place, 

closely  following  the  method  previously  outlined  with 
regard  to  the  cervical  and  incisal  preparation.  The  backing  should  then 
be  adjusted  to  place  on  the  facing  and  burnished  to  a  close  adaptation 
with  the  porcelain,  after  trimming  away  all  unnecessary  surplus  around 
the  edges. 

The  two  should  then  be  placed  in  position  on  the  cap  and  the  relation 
sustained  with  hard  wax  (Fig.  137  C),  the  facing  removed  and  the  metal 
parts  invested  and  soldered  (Fig.  137  D). 

After  finishing  the  crown  the  facing  should  be  attached  with  cement, 
or  gutta  percha,  and  the  crown  mounted.    Because  of  the  extreme  thinness 


i63 


and  pliability  of  the  backing  surrounding  the  attachment,  this  style  of 
facing  is  also  applicable  to  the  construction  of  the  shell  or  telescope  crown 
with  porcelain  facing,  and  to  bicuspid  and  anterior  dummies  for 
bridgework. 

Another  design  has  recently  been  devised  by  Dr. 

DwIflbt'S  Tacltlfl.       W.  H.  Dwight,  of  Le  Mars,  Iowa.    This  consists  of 

a  facing  containing  a  countersunk  platinum  socket, 

which  engages  the  arms  of  a  bifurcated  spring  post,  with  threaded  shank, 

which  is  to  be  previously  attached  to  the  backing  (Fig.  138  A). 

In  the  application  of  this  principle  the  cap  should 
Hpplication.  be  constructed  as  indicated,  and  the  models  secured. 

The  facing  should  then  be  selected  and  ground  to  place 
with  the  incisal  end  properly  beveled  to  afford  protection.  By  heating  the 
facing  and  pressing  its  labial  or  buccal  surface  against  a  small  piece  of 
ordinary  sealing  wax  it  may  be  conveniently  handled  during  the  process 
of  adaptation. 


When  the  grinding  has  been  completed  the  spring  post  should  be 
inserted  in  the  socket  of  the  facing  and  the  end  of  its  projecting  shank 
imprinted  in  the  surface  of  a  piece  of  pure  gold,  about  34  gauge,  to 
denote  the  location  of  a  perforation  for  its  reception. 

The  perforation  should  then  be  made  with  a  punch  or  small  sharp- 
pointed  instrument,  and  the  projecting  threaded  shank  screwed  into  it 
until  the  backing  approximates  the  shoulder  of  the  post.  This  may  be 
facilitated  by  leaving  the  facing  attached  or  by  the  use  of  a  wrench 
designed  for  the  purpose.  The  facing  should  then  be  removed  (Fig. 
138  B),  and  post  and  backing  permanently  attached  by  the  use  of  a  small 
quantity  of  solder  fused  around  the  line  of  junction  upon  the  surface  to 
be  placed  next  to  tJie  porcelain,  in  order  to  stiffen  and  strengthen 
their  union. 

The  facing  is  now  replaced  and  the  backing  burnished  and  trimmed 
to  a  proper  adaptation  with  the  porcelain  and  then  placed  in  position  on 
the  cap  and  the  relation  sustained  with  hard  wax. 


i64 

After  removing  the  porcelain  the  inner  surface  of  the  backing  should 
be  coated  with  a  solution  of  whiting  and  the  parts  invested,  soldered  and 
finished  (Fig.  138  C).  In  permanently  attaching  the  facing  to  the  crown 
the  arms  of  the  post  should  be  expanded  until  it  becomes  necessary  to  use 
some  little  pressure  in  forcing  it  to  place,  as  they  are  purposely  left 
slightly  contracted,  in  order  to  admit  of  easy  adjustment  during  the 
process  of  adaptation. 

The  facing  should  then  be  cemented  to  place  and  the  crown  polished 
and  mounted. 

The  same  principle  is  also  applicable  to  the  replacement  of  broken 
facings  on  crowns  otherwise  constructed,  and  will  receive  subsequent 
consideration  in  that  connection. 

While  the  details  are  expeditious  and  simple,  the  principle  involved 
m  this  style  of  attachment  seems  weak,  from  the  fact  that  the  mechanical 
fixation  is  insecure,  and  depends  much  upon  the  presence  of  cement  for 
the  necessary  strength. 

The  method  of  constructing  a  replaceable  facing, 

Bryant's  method.      devised  and  practiced  by  Dr.  Emory  A.  Bryant,  of 

Washington,  D.  C,  consists  of  forming  a  box  for 

the  accommodation  of  the  pins   as  a  portion    of    the    backing,    and    is 

applicable  to  any  size  of  the  ordinary  cross-pin  flat-back  facings,  and  to 

the  construction  of  bridgework  as  well  as  single  crowns. 

In   the    application   of  this    method    the   facing 

Jlpplication.  should   be  selected  and   ground   to  the  proper  and 

desired  adaptation,  after  which  it  should  be  backed 
with  pure  gold  or  platinum  (34  to  36  gauge),  as  the  requirements  of 
construction  may  indicate. 

In  the  box  method  a  pair  of  Barnard's  parallel 

Box  metbod.  pliers,  modified  by  the  addition  of  a  set  screw  and 

by  grinding  down  the  ends  of  the  beaks  to  approxi- 
mate the  diameter  of  the  pins  of  the  facing,  as  indicated  in  Fig.  139,  are 
now  accurately  adjusted  to  the  relation  of  the  pins,  and  a  strip  of  platinum, 
36  gauge,  somewhat  wider  than  the  length  of  the  pins,  is  then  wrapped 
around  the  points  of  the  pliers,  forming  a  box  for  the  reception  of  the 
pins. 

After  soldering  the  joint,  backing  and  box  are  adjusted  to  position 
on  the  facing,  and  their  relation  marked  with  a  sharp-pointed  instrument, 
after  which  they  are  removed  and  attached  by  soldering.  The  two  per- 
forations for  the  ])ins  should  now  be  extended  into  one  by  cutting  out 
the  metal  between  them  with  a  fissure  bur  of  about  the  same  diam- 
eter (Fig.  140  A). 

This  should  then  be  readjusted  to  position  on  the  facing,  and  the  inner 


i65 


edge  of  the  box,  and  the  ends  of  the  pins  trimmed  to  approximate,  and 
imtil  the  projection  offers  no  obstruction  to  the  desired  contour  or  occlu- 
sion. A  cover  of  22  karat  gold,  about  28  gauge,  somewhat  larger  than 
the  box,  is  soldered  to  this  edge  from  the  outside,  and  subsequent^ 
trimmed  until  all  surplus  is  removed,  which  completes  the  construction 
of  the  backing.     (Fig.  140  B.) 

The  facing  should  be  prepared  by  slightly  serrating  the  surfaces 
of  the  pins  which  present  toward  each  other,  and  then  filling  the  space 
between  them  with  soft  solder,  using  enough  to  fill  it  at  least  equal  to 
the  length  and  thickness  of  the  pins. 

This  may  be  easily  done  by  first  fluxing  the 
pins  with  soft  solder  flux,  placing  the  soft  solder 
or  fusible  alloy  in  position,  and  carefully  direct- 
ing- the  flame  upon  the  porcelain,  until  it  takes 
hold  of  the  pins,  after  which  it  should  be  quickly 
plunged  into  cold  water  to  preclude  an  expan- 
sion of  the  pins,  which  might  cause  fracture  of 
the  porcelain.  Or  the  facing  may  be  placed  on 
a  charcoal  block  or  asbestos  pad,  pins  upward. 


Bq.l^O 


and  the  solder  fused  by  carefully  directing  a  small  flame  upon  the 
porcelain. 

This  extension  of  soft  solder  should  be  filed  down  even  with  the 
pins  on  all  surfaces  (Fig.  140  C),  except  that  the  extreme  end  should 
remain  a  shade  heavier  or  thicker,  to  facilitate  the  subsequent  attachment 
to  the  backing  with  cement. 

Facing  and  backing  should  be  adjusted,  placed  in  proper  relation 
with  the  cap  and  temporarily  attached  with  hard  wax.  The  facing  should 
then  be  removed  and  the  box  filled  with  moistened  whiting,  and  a  staple 
of  German  silver  or  iron  wire  inserted,  with  the  ends  projecting  about 
one-quarter  of  an  inch.  This  prevents  the  solder  from  penetrating  the 
interior  of  the  box,  and  precludes  any  change  in  the  relation  of  box  and 
backing  during  the  process  of  soldering.  The  parts  should  be  invested, 
soldered  and  finished  as  usual  and  the  facing  then  mounted  with 
cement. 


i66 

A  similar  method  involves  the  like  adaptation  of 

tube  WctftOd.         a  separate  tube  to  each  individual  pin,  but  as  this 

entails  much  more  work,  possesses  less  strength  and 

affords  less  opportunities  for  replacing  the  facing  in  case  of  accident,  it 

has  been  almost  entirely  superseded  by  the  former  procedure. 

The  merit  possessed  by  these  methods  lies  in  the  facility  with  which 
a  replaceable  facing  and  its  attachment  may  be  constructed,  and  the  main 
advantage  in  their  use  may  be  attributed  to  the  fact  that  the  facing  is  not 
held  so  unyieldingly  rigid  as  if  soldered. 

Another  method  of  greater  simplicity  and  in- 
CbC  Boos  method.  creased  practicability  is  known  as  the  "Boos"  Method. 
This  also  involves  the  use  of  ordinary  long-pin 
facings,  but  the  method  of  forming  the  attachment  to  the  backings  is 
much  easier  and  quicker,  as  well  as  being  equally  secure.  Its  application, 
however,  together  with  the  similar  use  of  Davis  crowns,  will  be  subse- 
quently considered. 

Jlpplicdtion  to  Bicuspids  and  molars. 

The  band  and  dowel  style  of  construction  is  applicable  to  the  restora- 
tion of  the  crowns  of  bicuspids  and  molars  as  well  as  to  the  anterior  teeth, 
but  is  more  generally  indicated  and  more  extensively  employed  upon 
bicuspids  than  upon  molars. 

While  it  is  especially  indicated  in  porcelain  work, 
Indications.  where  the  root  is  necessarily  and  purposely  trimmed 

to  approximate  the  gingival  line,  it  is  also  indicated  in 
combination  with  gold,  in  order  that  the  work  may  more  closely  approach 
the  highest  esthetic  requirements.  In  this  connection,  and  in  the  absence 
of  facilities  for  doing  porcelain  work,  a  facing,  or  saddleback  or  rubber 
tooth  may  be  used  with  artistic  results,  and  particularly  where  the  short- 
ness of  the  root  demands  the  employment  of  a  dowel  attachment,  in  prefer- 
ence to  restoring  its  coronal  proportions  with  amalgam,  and  using  a  shell 
or  telescope  crown. 

The  application  is  more  generally  indicated  and 
Bicuspids.  more    practical    on    the    bicuspids,    because    of    the 

necessity  for  observing  higher  artistic  possibilities, 
and  of  the  objection  to  placing  gold  crowns  upon  these  teeth. 

In  the  restoration  of  molars,  however,  the  indica- 
molars.  tions  are  not  so  general,  and  the  range  of  application 

is  more  limited,  for  the  reasons  that  such  crowns  are 
usually  beyond  the  range  of  vision,  at  least  to  an  extent  which  greatly 
diminishes  the  esthetic  requirements;  that  they  are  subjected  to  more 
vigorous  strain  in  the  act  of  mastication,  and  that  a  telescope  attachment 
to  a  projecting  end  of  the  root  doubtless  affords  greater  strength  and 


1 67 

more  permanent  stability  than  is  usually  obtained  by  cutting  the 
remaining  root  down  to  the  gingival  line  and  using  a  dowel  attachment. 

It  is  claimed  by  some,  however,  that  the  preparation  of  a  short  root 
and  the  subsequent  adaptation  of  a  narrozv  band,  with  accuracy,  is  so 
facilitated  as  to  present  advantageous  features,  as  compared  with  the  more 
extensive  preparation  of  the  remaining  coronal  proportions  of  the  root  for 
the  shell  or  telescope  crown. 

Yet  such  a  claim  -  everts  to  the  manner  of  the  execution  of  the  neces- 
sary details,  and  as  they  must  be  carefully  and  skilfully  observed  in  either 
instance,  the  advantage  seems  more  hypothetical  than  practical,  and  the 
judicious  preservation  of  tooth  structure  combined  with  the  stability  of 
attachment  as  applied  particularly  to  the  molar  teeth,  for  the  reasons 
mentioned,  should  precede  a  consideration  of  facility  and  possible  advan- 
tages in  the  construction. 


Proccaurc. 

In  the  construction  of  this  style  of  crown,  in  combination  with  gold, 
tzvo  more  or  less  practicable  methods  are  employed,  and  they  differ  only 
in  the  style  of  porcelain  facing  or  tooth  used.  The  cap  should  be  com- 
pleted as  though  for  an  anterior  crown,  as  described,  and  the  dowel  fitted 
and  soldered. 

Where  a  heavier  and  stronger  cap  than  will  be 
Kccnforced  Cap.  afiforded  by  the  thickness  of  the  band  is  indicated  or 
desirable,  the  same  may  be  obtained  by  allowing  the 
floor  to  extend  or  project  about  V32  of  an  inch  from  the  band,  and  then 
filling  in  until  flush  and  smooth  with  22  or  20  karat  solder.  This  will 
result  in  a  cap  possessing  good  adaptation,  a  maximum  degree  of  strength 
and  a  minimum  tendency  to  cause  irritation,  such  as  is  frequentlv 
indicated  in  the  restoration  of  bicuspid  crowns. 

If  the  use  of  two  dowels  should  become  necessary 
Use  Of  two  DOWCiS'  to  insure  sufficient  stability,  care  should  be  observed 
to  have  them  inserted  at  such  an  angle  as  to  pass  into 
the  root  readily,  and  yet  project  through  the  floor  of  the  cap  at  a  point 
at  which  they  will  offer  little,  if  any,  obstruction  to  the  proper  adjustment 
of  the  facing.  While  the  surplus  ends  may  be  cut  away  reasonably  close 
to  the  floor  after  soldeniig,  the  longer  they  may  be  allowed  to  remain  the 
greater  the  strength  of  their  attachment  to  the  crown. 

The  bite  and   impression  should   follow   in   the 
Bite  and  Impression,     "sual  manner,  and  the  models  then  be  obtained  and 
mounted  upon  the  articulator. 


i68 

Use  of  Tlat-BacR  Taclng. 

The  method  perhaps  most  usually  employed  involves  the  use  of  a 
fiat-back  facing  and  gold  cusps,  and  while  this  style  of  construction  pos- 
sesses the  advantage  of  strength,  it  also  presents  the  objectionable  feature 
of  the  presence  of  an  occlusal  surface  of  gold. 

The  facing  should  be  selected  and   ground  to 
facing.  position  on  the  cap,  and  the  occlusal  end  then  ground 

to  allow  for  the  presence  of  the  cusp,  and  properly 
beveled,  as  indicated.  It  should  then  be  backed  up  with  a  single  backing 
of  pure  gold,  about  34  gauge,  which  should  be  closely  finished  down  to  the 
edges  at  all  points,  except  on  the  occlusal,  w^here  a  slight  projecting  surplus 
should  remain. 

Facing  and  backing  should  now  be  placed  in 
€u$p$.  position  on   the   cap   and  sustained  with  hard  wax 

(Fig.  141  A),  while  the  cusps  are  being  formed  and 
fitted  bv  whatever  method  selected. 


These  may  be  accurately  obtained  by  allowing  one  or  both  of  the  pins 
to  project  away  from  the  backing,  pouring  soft  plaster  into  the  space 
and  up  against  them,  and  closing  the  articulator,  and  then  subsequently 
carving  them  and  securing  dies  in  the  manner  already  outlined.  The  pins 
are  allowed  to  project  as  a  means  of  securely  sustaining  the  plaster  during 
the  process.  Or  the  cusps  may  be  obtained  from  any  of  the  die  and  die- 
plate  systems. 

After   swaging,  the  buccal  portion  of  the  gold 

Adaptation.  should  be  cut  away  to  the  occlusal  angle  on  a  plane 

which  will  admit  of  approximating  it  with  the  edge 
of  the  facing  and  backing.  This  will  leave  only  the  thicknesses  of  the 
gold  forming  the  cusp  and  the  backing  along  the  occlusal  edge,  but  the 
same  will  aft'ord  ample  jirotection  to  the  porcelain,  and  admits  of  a  more 
esthetic  result. 

After  thus  trimming  the  cusp  to  adaptation  with  the  porcelain  the 
two  should  be  adjusted  to  the  cap  with  wax  and  adapted  to  the  articula- 
tion and  occlusion.     (Fig.  141  B.) 


i69 

While  all  soldering  may  be  done  at  the  time  of  uniting  cusp,  facing 
and  cap,  it  is  usually  best  to  remove  the  cusp  and  facing  in  their  proper 
relation,  and  previously  invest  and  attach  them  with  a  sufficient  quantity 
of  20  karat  solder  to  effect  union  and  fill  the  lingual  portion  of  the  cusps. 

To  preclude  the  checking  of  the  facing  along  the  edge,  as  a  result  of 
the  impingement  of  the  cusps  occasioned  by  the  shrinkage  of  the  solder, 
a  slight  space  should  be  allowed  between  the  backing  and  cusps,  and  this 
filled  with  wax  to  prevent  the  investment  material  from  running  in. 

When  the  parts  are  securely  sustained  with  wax 
Jlpproximal  Restoration,  enough  should  be  further  added  to  form  the  proper 
approximal  contour  to  secure  a  restoration  of  contact, 
and  a  small  piece  of  pure  gold,  about  36  gauge,  should  then  be  adapted 
or  burnished  to  each  approximal  side  of  the  crown,  extending  from  cusp 
to  cap,  and  held  in  place  with  the  wax.  This  forms  a  matrix  which  facili- 
tates soldering  and  gives  the  desired  approximal  contour,  but  should  not 
extend  over  the  lingual  portion  of  the  wax,  as  the  solder  must  be  subse- 
quently added  from  this  point. 

Foil  gold,  No.  60  or  120,  may  also  be  used  for  the  same  purpose,  if 
desired. 

The    crown    should   be    invested   with    a    slight 

TnOCStitld.  covering  over  and  up  to  the  edges  of  the  pure  gold 

matrices  to  hold  them  in  place,  but  with  the  lingual 

surface  freely  exposed.    When  the  investment  has  been  properly  trimmed, 

the  wax  should  be  carefully  picked  out  and  the  remainder  removed  by 

pouring  boiling  water  upon  it,  and  the  parts  then  fluxed  and  heated. 

The  soldering  should  be  done  by  the  consecutive 
Seldcrlng.  application  of  small  pieces  of  18  karat  solder,  of  a  size 

suitable  to  be  readily  dropped  into  the  opening.  Small 
balls  of  scrap  gold  and  silver  are  sometimes  used  to  aid  in  filling  in 
when  the  space  is  of  considerable  size,  and  the  use  of  the  same  facilitates 
the  procedure  and  lessens  the  extent  of  shrinkage  which  would  take  place 
in  the  use  of  solder  alone.  The  use  of  balls  of  German  silver  or  copper 
is  also  permissible  if  they  are  well  and  completely  covered  over  with 
the  gold  solder. 

In  finishing,  care  should  be  exercised  to  preserve  the  approximal 
contour,  in  order  that  contact  may  be  properly  restored  and  the  crown 
then  polished  and  mounted.     (Fig.  141  C.) 

These  crowns  are  sometimes  constructed  without  cusps,  but  such 
practice  is  to  be  condemned,  except  in  rare  instances  on  first  bicuspids, 
because  the  usefulness  of  any  crown  is  usually  equal  in  importance  to 
cosmetic  effect. 


170 


Use  or  SiiddlC'BdCk  CeetD. 

A  variation  of  method  consists  in  employing  the  so-called  saddle- 
back tooth  instead  of  the  facing,  and  while  this  style  of  construction  pos- 
sesses the  advantage  of  presenting  an  occlusal  surface  of  porcelain,  and 
thus  avoiding  any  display  of  gold,  the  more  esthetic  result  is  probably 
obtained  at  the  expense  of  strength,  as  the  thin  lingual  portion  of  such 
porcelain  teeth  is  usually  inherently  weak  and  more  or  less  easily  broken. 
Where  the  stress  of  occlusion  is  light,  however,  they  may  often  be  used 
to  good  advantage. 

In  their  application  a  selection  should  be  made 
Proc(dUf(.  which  possesses  as  broad  a  neck  as  will  be  required 

to  make  a  perfect  joint  with  the  cap,  and  which  will 
restore  the  contact  with  adjacent  teeth. 

It  should  then  be  ground  to  meet  these  requirements,  and  to  properly 
occlude  and  articulate,  after  which  a  single  backing  of  about  34  gauge 
pure  gold  should  be  well  adapted,  attached  by  bending  the  pins,  and 
trimmed  to  closely  follow  the  edges  of  the  porcelain  without  overhanging, 
(Fig.  142  A.) 


Ficj.  142. 

The  proper  relation  to  the  cap  should  now  be  obtained  (Fig.  142  B) 
and  securely  sustained  with  hard  wax,  and  the  crown  invested  in  such 
manner  as  to  have  the  porcelain  covered,  but  to  leave  the  backing  freely 
exposed. 

In  soldering,  a  sufficient  quantity  of  18  karat  solder  (in  addition  to 
the  use  of  balls  of  metal,  if  desirable),  to  afford  ample  and  adequate 
contour  of  the  approximal  and  lingual  surfaces,  should  be  used.  Fig. 
142  C  illustrates  the  finished  crown. 

An  ordinary  vulcanite   tooth   may  also  be  em- 

U$e  Of  Uulcanite       ployed  in  similar  manner,  and  in  crowns  of  consider- 

teetb.  able    length    sometimes    to    even    better    advantage, 

because  of  possessing  more  strength  in  the  lingual 

cusp,  due  to  the  greater  body  of  porcelain  surrounding  the  pins. 

In  their  use  the  heads  of  the  pins  should  be  compressed  between  the 
beaks  of  pliers,  or  cut  off,  and  the  lingual  surface  ground  smooth  to 
facilitate  the  adaptation  of  the  backing  and  the  above  procedure  observed. 


171 
Jlpplication  or  Remoi^able  €rown$. 

Previous  to  the  modern  methods  of  successfully  treating  chronic 
alveolar  abscesses,  the  construction  of  crowns  which  could  be  temporarily 
removed  from  their  attachment  to  the  root  and  easily  replaced  was  advo- 
cated and  practiced  as  a  means  of  permitting  the  necessary  therapeutic 
treatment  of  roots  so  affected. 

At  the  present  time,  however,  such  practice,  for  this  purpose,  has 
become  almost,  if  not  entirely,  obsolete,  and  the  application  of  such  crowns 
is,  in  consequence,  indicated  only  in  the  construction  of  removable  hridge- 
zvork;  hence,  their  indications  and  usefulness,  together  with  the  various 
methods  of  construction  employed,  will  be  subsequently  considered. 

Jlpplication  to  Trrcdularities. 

Since  some  cases  and  forms  of  irregularities  are  not  always 
amenable  to  the  usual  process  of  treatment  for  their  correction,  because 
of  the  age  of  the  patient,  the  poor  character  of  the  teeth,  their  position  in 
the  arch,  or  other  physiological  or  pathological  reasons,  it  sometimes 
becomes  warrantable  to  sacrifice  the  natural  crowns  and  effect  artificial 
substitution,  which  will  relieve  the  disfigurement  thus  occasioned. 

As  the  radical  or  injudicious  destruction  of  the  natural  crowns  of 
teeth  must  be  regarded  as  presenting  a  serious  aspect,  and  particularly 
when  involving  the  anterior  teeth,  where  they  are  necessarily  sacrificed 
to  the  gingival  line,  a  careful  study  of  the  existing  conditions  must  be 
made,  in  order  that  it  may  be  wisely  determined  that  such  a  procedure 
is  justifiable. 

The      two      general     classes     indicating     such 

Indications.  treatment    as    a    means    of    improving   both    useful- 

ness and   cosmetic   effect,  are  those  resulting  from 
malposition,  and  a  diminution  of  the  normal  space  caused  by  gravitation. 

malposition. 

Cases  are  not  uncommon  wherein  the  malposition  of  one  or  more 
teeth,  as  previously  indica;v.d  in  Fig.  31,  may  be  best  corrected  by  the 
application  of  artificial  crowns,  but  the  achievement  of  successfullv  artistic 
and  hygienic  results  in  such  instances  will  depend  nuich  upon  a  close 
observation  of  the  necessary  details  of  construction. 

In     the     construction     of     crowns     for      such 
Construction.  extreme  cases,  as  is  illustrated  in  Fig.  !_(:;,  the  cap  and 

dowel  should  be  adapted  to  the  root,  as  usual,  and 
the  bite  and  impression  taKen  and  models  secured. 


172 

An  extension  from  the  cap  which  will  afford 
Extension  Tor  Support    a   close   adaptation   to   the  tissue,  and  a  practically 

of  Taclng.  unyielding  support  to  the  facing  when  placed  in  its 

proper  position  of  alignment,  should  then  be  made  by 
burnishing  a  piece  of  pure  gold,  34  to  36  gauge,  to  the  model. 

When  the  desired  shape  and  conformation  have  been  obtained,  the 
extension  should  then  be  imbedded  into  the  model  at  least  equal  to  its 
thickness  by  first  marking  the  outline  and  then  uniformly  scraping  the 
surface. 

The  cap  should  then  be  detached  from  the  model  and  both  cap  and 
extension  again  placed  in  position  and  their  relation  sustained  with 
hard  wax. 

The  parts  should  now  be  removed  and  invested,  and  subsequently 
united  with  adequate  re-enforcement.  This  can  be  best  accomplished  by 
trimming  a  piece  of  clasp  metal  or  22  karat  plate,  28  to  30  gauge,  of 


/7a, /43- 


proper  size  to  rest  upon  the  cap  and  cover  the  extension,  and  then  uniting 
the  whole  with  20  karat  solder. 

This  should  then  be  replaced  in  position  on  the  model,  and  the  crown 
completed  in  the  usual  manner. 

The  hygienic  qualities  possessed  by  crowns  so 
l^yglcnlc  Con-         constructed  depend,  of  course,  upon  the  adaptation  of 
Siderations.  the  extension  and  facing  to  the  tissues  upon  which 

they  rest;  but  the  burnishing  (or  swaging,  if  more 
desirable)  of  the  extension  admits  of  a  close  conformation,  and  the 
scraping  of  the  surface  of  the  model  beneath  it  and  the  neck  of  the  facing 
so  increases  the  bearing  upon  the  tissue  as  to  usually  result  in  an  adapta- 
tion of  the  finished  crown  which  will  preclude  the  lodgment  and  accumula- 
tion of  debris. 

Diminution  of  normal  Space. 

A  condition  which  is  a  phase  of  malposition  caused  by  the  natural 
tendency  of  teeth  to  gravitate  toward  an  unoccupied  space  in  the  arch 


is  illustrated  in  Fig.  144,  where,  from  the  extensive  destruction  of  the 
natural  crown  by  caries,  the  adjacent  teeth  have  moved  together,  until 
the  space  formerly  existing  in  the  normal  relation  is  much  reduced. 

In  such  conditions,  when  involving  any  of  the  ten  anterior  teeth,  the 
application  of  an  artificial  crown  of  adequate  and  proportionate  size  would 
be  impossible,  of  course,  unless  sufficient  accommodation  be  previously 
gained  by  separating  the  teeth,  and  such  a  procedure  is  indicated,  and 
becomes  essentially  necessary,  if  the  highest  artistic  results  are  to  be 
obtained. 

In  separating  the  teeth  in  such  instances  the 
Separation  of  Cectb.  application  of  a  simple  regulating  appliance  may 
become  necessary  if  any  great  deal  of  space  is  to 
be  gained,  and  when  the  desired  space  has  been  obtained  it  may  be  pre- 
served during  the  construction  of  the  crown  by  wedging  with  a  small 
piece  of  wood,  or  by  tightly  packing  with  gutta  percha  or  temporary  stop- 
ping during  intervals  between  sittings. 


Sufficient  separation  may  often  be  secured  in  a  more  simple  manner 
by  trimming  and  closely  fitting  a  wedge  of  soft  wood,  previously  com- 
pressed in  a  small  bench-vise,  into  the  space.  If  the  wood  is  properly 
trimmed  to  follow  the  outlines  of  the  adjacent  teeth,  so  that  it  may  be 
worn  with  some  degree  of  comfort,  and  then  tightly  fitted  into  the  space, 
having  the  surfaces  approximating  the  adjacent  teeth  slightly  concaved 
to  hold  it  in  position,  and  the  grain  placed  parallel  with  the  long  axis  of 
the  tooth,  the  absorption  of  moisture  will  usually  produce  an  expansion 
sufficient  to  create  the  space  desired.  This  may  also  be  increased  some- 
what by  the  use  of  an  intervening  layer  of  cotton  or  tape  when  necessary. 

Jlpplication  of  tbe  Tntraaental  Band. 

For  the  purpose  of  avoiding  the  necessary  peripheral  preparation  of 
the  root  and  the  possible  irritating  influence  of  a  band,  and  at  the  same 
time  securing  the  additional  stability  afiforded  by  the  latter  to  the  attach- 
ment of  a  dowel  crown,  the  iiifradeiifal  band  has  been  devisod. 

The  principle  involved  is  similar  to  that  of  the  original  Biittner  crown 
in  which  the  periphery  of  the  root  was  trephined  so  as  to  form  a  seat 


174 


for  the  accommodation  of  the  band.  In  the  appHcation  of  the  intradental 
band,  however,  a  groove  is  trephined  into  the  root  midway  between 
the  pulp  canal  and  the  periphery,  and  a  band  subsequently  fitted  into 
the  groove. 

The  design  was  probably  originally  suggested  and  patented  by  Dr. 
Moses  Rynear,  of  New  York,  in  1886,  but  subsequent  patents  have  been 
obtained  on  modifications  of  this  by  Dr.  J.  Leon  Williams,  of  London, 
and  Dr.  B.  J.  Cigrand,  of  Chicago,  in  both  of  which  the  principle  is  the 
same,  but  the  application  and  details  differ  somewhat. 

While  the  advantages  claimed  by  the  advocates  for  this  mode  of  con- 
struction are  doubtless  desirable,  they  are  obtained  at  the  expense  of  the 
integrity  of  the  basal  portion  of  the  root,  and  for  this  reason  are  indicated 
only  on  large,  strong  roots,  entirely  free  from  decay,  and  will  probably 
never  become  more  generally  applicable. 


f^Y 


14.5. 


F/gJ46. 


The  design  and  method  devised  and  employed 
Ulilliams'S  lUctbOd.     by  Dr.  Williams  consists  of  a  series  of  ready-made 
platinum  caps  and  dowels  in  graded  sizes,  together 
with  suitable  trephines  and  root  canal  drills. 

In  the  application  of  this  style  of  crown  the  root 
JVpplicatiOlt.  is  prepared  as  usual  for  a  dowel  crown,  without  a 

band.  A  cap  (Fig.  145  A)  of  suitable  and  propor- 
tionate size  is  then  selected  from  the  series,  and  the  trephine  and  drill  of 
corresponding  size  selected. 

The  canal  is  first  enlarged  with  the  drill  (Fig.  145  B)  to  accommodate 
the  dowel,  and  the  trephine  then  used  to  cut  the  groove  for  the  reception 
of  the  band,  and  the  proper  relation  between  the  two  is  secured  by  the 
guide  post  in  the  center  of  the  trephine.     (Fig.  145  C.) 

When  the  cap  has  been  thus  closely  adapted  to  the  canal  and  groove, 


175 

the  surplus  floor,  which  is  about  34  to  36  gauge,  should  be  trimmed  to 
follow  the  peripheral  outline,  and  burnished  to  the  desired  adaptation  with 
the  entire  surface  of  the  root. 

The  bite  and  impression  should  then  be  taken  and  the  crown  com- 
pleted in  the  usual  manner  and  mounted  with  cement. 

The  facility  with  which  these  ready-made  caps  may  be  secured  and 
adapted  to  the  root  in  the  use  of  this  method  expedites  the  detail  of 
construction,  but  the  band  seems  too  thin  and  narrow  and  the  dowel 
too  slender  to  afford  adequate  strength  and  stability  to  a  crown  of  average 
requirements. 

The  method  devised  by  Dr.  Cigrand  constitutes 
Cfflrand's  method,     making  the  band  and  cap  and  adjusting  the  dowel, 
and   the    necessary   outfit   consists   of   two    sizes   of 
trephines  and  a  measurement  gauge,  as  previously  illustrated  in  a  consid- 
eration of  the  treatment  of  "fractured  roots." 

In  the  application   of  this  method  the  root  is 

Jlpplication.  prepared  as  indicated,  and  the  groove  cut  as  deep  as 

practicable  with  the  trephine  of  proportionate  size. 
The  band  is  then  cut  the  exact  length  indicated  by  the  measurement  guide 
for  the  size  trephine  used,  about  one-eighth  of  an  inch  wide  and  of  30 
gauge  gold,  22  karat,  or  platinum,  made  in  circular  form,  the  edges 
abutted,  and  soldered  with  a  very  small  bit  of  solder. 

It  should  then  be  fitted  over  the  end  of  the  measurement  mandrel  to 
give  it  the  proper  form,  and  adjusted  to  position  in  the  groove  by  gently 
forcing  to  place. 

The  surplus  end  extending  from  the  root  should  be  allowed  to  remain 
to  facilitate  removal  and  filed  smooth  on  a  parallel  line  with  the  surface 
of  the  root.  It  should  then  be  removed  and  soldered  to  a  floor  of  pure 
gold  or  platinum,  34  gauge,  somewhat  larger  than  necessary,  with  a 
minimum  of  solder. 

The  edge  of  the  band  previously  fitted  into  the  groove  should  now 
be  trimmed  away  until  the  floor  rests  firmly  against  the  root,  when  in 
position,  after  which  it  should  be  trimmed  and  burnished  to  the  proper 
adaptation. 

The  canal  should  now  be  prepared,  the  dowel  fitted,  and  then  soldered 
to  the  cap,  as  indicated,  and  the  crown  completed  in  the  usual  manner. 

The  completed  crown  and  the  relation  it  should  bear  to  the  root  in 
both  of  these  methods  is  illustrated  in  Fig.  146. 

Repairing  and  K^moving. 

Because  of  the  presence  of  porcelain,  and  the  consequent  more  or 
less  frequent  occurrence  of  fractured  facings  as  a  result  of  accident,  in- 


adequate  protection,  or  faulty  articulation  and  occlusion,  as  well  as  for 
the  purpose  of  replacement  or  substitution,  it  often  becomes  necessary 
to  repair  this  style  of  crown,  or  to  remove  it  from  its  attachment  to  the 
root. 

The  presentation  of  fractured  or  broken  facings  on  crowns  and 
bridges  constitutes  a  large  per  cent  of  the  failures  requiring  such  atten- 
tion, and  where  the  work  remains  otherwise  in  good  condition,  and  is 
secure  in  its  attachment,  repair  may  be  effected  in  an  artistic  manner  by 
replacing  the  facings  without  removing  the  piece. 

In  the  replacement  of  facings,  several  good  and 

Kcplac^mcnt  of         reliable  methods  are  employed,  but  a  selection  of  the 

TacingS.  best  or  most  desirable  one  will  depend  much  upon 

the  construction  of  the  work  and  the  requirements  of 

the  case,  as  well  as  the  individual  preference  of  the  operator. 

When  such  a  procedure  is  indicated,  where  the  work  has  been  con- 
structed by  the  ordinary  method,  all  remaining  particles  of  porcelain  sur- 
rounding the  pins  should  first  be  broken  and  removed.  This  can  be  quite 
easily  accomplished  with  excising  forceps,  cutting  pliers  or  chisels,  after 
which  the  projecting  pins  should  be  cut  away  and  ground  down  flush 
and  even  with  the  surface  of  the  backing,  with  a  sharp,  round,  or  oval, 
plain,  or  plug-finishing  bur. 

The  method  usually  and,  perhaps,   most  com- 
Usual  method.         monly  employed  consists  of  securing  the  attachment 
of  the  replaced  facing  by  simply  bending  or  clinching 
the  pins  upon  the  lingual  surface  of  the  backing. 

In  this  procedure  a  facing  of  the  required  size. 

Procedure,  shape  and  color  should  be  selected,  and  the  backing 

then  properly  perforated  to  admit  of  its  adjustment. 

The  accurate  position  of  the  perforations  may  be  easily  ascertained, 

and  designated,  by  first  coating  the  surface  of  the  backing  with  a  thin 

film  of  melted  wax,  and  then  pressing  the  ends  of  the  pins  into  it,  after 

noting  that  they  have  been  made  parallel  zvith  each  other,  and  that  the 

facing  is  held  in  its  proper  relation  to  the  backing  and  adjacent  teeth  or 

facings. 

When  the  exact  location  has  been  thus,  or  otherwise,  designated,  the 
perforations  may  be  made  with  a  small  spear-pointed  drill,  and  subse- 
quently enlarged  to  the  proper  proportions  to  receive  the  pms  with  a 
round  or  fissure  bur,  or  twist  drill,  of  corresponding  diameter.  While 
they  should  be  large  enough  to  readily  admit  of  the  reception  of  the  pins, 


177 

the  fit  should  be  sufificiently  close  to  render  the  attachment  secure,  and 
preclude  the  subsequent  loosening  of  the  facing. 

The  facing  should  be  then  adjusted  to  position  and  ground  to  fit 
the  backing,  and  to  meet  the  requirements  of  length,  occlusion  and  align- 
ment ;  and  this  may  often  be  somewhat  facilitated  by  bending  the  incisal 
or  occlusal  edge  of  the  backing,  with  pliers,  until  a  more  favorable  shape 
presents. 

When  the  adaptation  has  been  completed,  it  should  be  noted  that  the 
pins  extend  through  upon  the  lingual  surface  sufficiently  far  to  admit  of 
securing  a  firm  attachment  by  bending  their  surplus  ends ;  and  in  the 
event  of  this  being  prevented  by  the  thickness  of  the  backing,  its  lingual 
surface  should  be  previously  ground  down  with  small  carborundum 
stones,  or  burs,  until  such  security  is  made  possible. 

The  surfaces  of  the  facing  and  backing  should  then  be  thoroughly 
cleaned,  slightly  roughened  and  dried  with  alcohol  or  chloroform,  when 


cj.m-l. 


the  backing  should  be  covered  with  cement  mixed  fairly  stiff,  and  the  fac- 
ing adjusted  to  position,  where  it  should  be  held  firnily  while  the  ends 
of  the  pins  are  being  bent  over  upon  the  backing  with  pliers. 

Moisture  should  then  be  excluded  from  the  cement  until  it  has  thor- 
oughly crystallized,  when  the  edge  of  the  backing  should  be  finished 
down  close  to  the  porcelain,  with  disks,  and  the  pins  flattened  with  small 
stones  until  presenting  a  more  or  less  smooth  and  continuous  contact  with 
the  backing.  The  latter  may  usually  be  ck)ne  to  the  best  advantage,  and 
with  the  least  danger  of  fracturing  the  cement,  at  a  subsequent  sitting. 


Brewer's  metbol 

The  above  procedure  is  much  simplified  and  greatly  facilitated  by 
the  use  of  a  pair  of  "riz'eiiiig  forceps,''  designed  for  the  purpose  of  rivet- 
g  the  ends  of  the  pins  down  close  upon  the  backing,  by  Dr.  Frank  A. 
Brewer,  St.,  of  King  City,  Cal.     (Fig.  147.) 


178 

One  beak  of  these  forceps  presents  a  corrugated  soft  rubber  pad,  on 
an  adjustable  joint,  which  admits  of  its  close  adaptation  to  the  facing 
at  any  angle  or  position,  while  the  other  presents  a  small  concave  steel 
point,  also  likewise  adjustable,  which  engages  the  end  of  the  pin. 

In  the  application  of  this  method  of  attaching 

Application.  the  facing,  the  perforations  should  be  made  and  the 

facing  adapted,  as  indicated,  and  then  the  ends  of 
the  pins  or  the  backing  should  be  sacrificed  until  the  former  project  only 
about  1/32  of  an  inch  beyond  the  surface  of  the  latter. 

The  lingual  surface  of  the  perforations  should  now  be  somewhat 
countersunk  with  a  round  bur  of  proper  size  used  in  a  right  angle  hand- 
piece. 

When  the  facing  has  been  well  adapted,  it  should  be  placed  in  posi- 
tion with,  or  without,  cement,  and  the  forceps  then  adjusted,  when  a  slight 
pressure  upon  the  handles  applied  during  a  rotary  or  swing- 
ing movement  of  the  arm  will  effect  an  expansion  of  the  diameter,  and  a 
compression  of  the  heads  of  the  pins,  until  a  very  secure  and  finished 
attachment  results,  with  little  or  no  danger  of  fracturing  the  porcelain. 

Underwood's  and  mitcbell's  method. 

The  method  advocated  by  Dr.  C.  J.  Underwood,  of  Elgin,  111.,  which 
in  similar  detail  has  also  been  employed  for  a  number  of  years  by  Dr. 
Wm.  Mitchell,  of  London,  England,  is  also  valuable  and  useful,  and  is 
particularly  applicable  to  those  cases  where  the  old  backing  was  origin- 
ally, or  has  been  worn  down  until,  too  short  to  afford  the  proper  pro- 
tection to  the  porcelain  along  the  incisal  or  occlusal  edge. 

This  method  consists  of  adapting  a  duplicate  backing  to  the  lingual 
surface  of  the  old  backing,  and  then  attaching  it  to  the  pins  of  the  facing 
with  solder,  and,  wherever  the  occlusion  will  admit,  its  application  may 
be  made  with  very  artistic  results,  and  with  a  maximum  of  strnegth. 

In  the  procedure  incident  to  the  application  of 

Jlpplication.  this   method,    the   remaining  porcelain   and   project- 

ing ends  of  the  pins  should  be  removed  from  the  old 
backing,  and  slois  or  grooves  sufficiently  wide  to  accommodate  the  pins 
of  the  new  facing  and  extending  from  the  incisal  or  occlusal  end  toward 
the  cervical  to  a  point  which  will  admit  of  its  proper  adjustment,  should 
be  made  with  a  cross-cut  or  plain  fissure  bur.     (Fig.  148  A.) 

The  location  of  these  grooves  may  be  accurately  designated,  as  pre- 
viously indicated,  and  the  bur  used  should  be  of  a  diameter  as  similar  to 
that  of  the  pins  as  possible. 

The  facing  selected  is  then  ground  to  the  required  and  desired  adap- 
tation, and  afterward  backed  up  with  pure  gold,  about  34  gauge.     This 


1/9 

should  be  well  adapted  to  the  incisal  or  occlusal  end  of  the  facing,  and 
trimmed  to  closely  follow  its  outlines.  The  cervical  edge  of  the  backing 
should  be  then  drawn  away  from  its  contact  with  the  porcelain  toward 
the  extreme  ends  of  the  pins,  so  as  to  straddle  or  pass  to  the  lingual  sur- 
face of  the  old  backing. 

Facing  and  backing  should  be  then  adjusted  to  position  on  the  crown 
or  bridge,  and  the  latter  burnished  to  a  close  conformation  with  the  lin- 
gual surface  of  the  old  backing,  which,  if  too  thick  to  allow  the  pins  to 
project  slightly  through  the  new  backing,  should  be  ground  until  admit- 
ting of  same.     (Fig.  148  B.) 

While  it  is  best  to  secure  this  adaptation  directly  in  the  mouth,  it  may 
also  be  accomplished  with  reasonable  accuracy  by  taking  an  impression 
of  the  crown  and  adjacent  teeth,  after  the  grooves  have  been  cut,  with 
gutta  percha,  and  obtaining  from  it  a  fusible  metal  working  model  for 
the  purpose. 


Ficj.l^Q, 


The  adaptation  should  then  be  sustained  by  the  use  of  wax  or  tem- 
porary stopping,  and  the  facing  and  backing  gently  detached,  and  in- 
vested with  sufficient  care  to  insure  the  thorough  penetration  of  the  in- 
vestment- material  into  the  intervening  space  between  the  two. 

The  relation  should  now  be  permanently  sustained  by  soldering  the 
backing  to  the  exposed  ends  of  the  pins,  and  then  re-enforcing  it  as  much 
as  the  occlusion  will  admit,  after  which  it  should  be  finished  and  polished 
(Fig.   148  C.)   and  then  mounted  with  cement. 

While  the  detail  of  this  method  is  necessarily  somewhat  circuitous, 
the  procedure  affords  a  most  secure  and  finished  result. 


Dwigbt's  mctbcd. 

Dwight's  method,  which  has  been  previously  mentioned  and  illus- 
trated in  connection  with  replaceable  and  detachable  facings,  is  also  ap- 
plicable to  the  repair  of  work  where  the  ordinary  two-pin  facing  has  been 
used. 


i8o 

When   the   remaining  porcelain   and  projecting 

JIppHcatiOn.  ends  of  the  pins  have  been  removed,  a  facing  of  this 

particular   style   should   be   selected   and   ground   to 

place,  in  which  the  procedure  is  facilitated  because  of  the  absence  of  any 

pins. 

After  the  proper  adaptation  has  been  secured,  the  "finder,"  which 
is  included  among  the  necessary  instruments  for  doing  this  special  work, 
and  consists  simply  of  a  base  or  shank  which  fits  into  the  socket  in  the  fac- 
ing, and  tapers  to  a  central  point,  should  be  adjusted  to  position.  (Fig. 
149  A.) 

This  affords  a  means  of  designating  the  exact  location  for  a  single 
perforation  in  the  old  backing,  by  applying  sufficient  pressure,  or  by  the 
use  of  a  thin  film  of  wax,  wath  the  facing  held  in  its  proper  relation. 


C 


Fiq.  1^9, 


A  small  perforation  should  first  be  made  at  this  point  with  a  drill  or 
round  bur,  and  this  then  suitably  enlarged  with  a  twist  drill,  and  subse- 
quently threaded  with  a  tap,  both  of  which  are  also  included  in  the  outfit. 
(Fig.  149  B.) 

The  threaded  shank  of  the  "attachment"  should  be  now  adjusted  to 
the  "holder"  (Fig.  149  C),  and  screwed  into  place  until  its  base  rests 
firmly  against  the  backing,  and  the  spring  ends  are  brought  into  proper 
position  to  engage  the  facing.  If  the  latter  is  impossible  at  the  first  trial, 
the  attachment  should  be  unscrewed  and  removed,  and  the  backing  im- 
mediately  surrounding  the  perforation   ground  away. 

By  this  means  the  threaded  area  may  be  gradually  diminished 
until  the  required  relation  is  obtained,  after  securing  which  the  projecting 
end  of  the  attachment  upon  the  lingual  surface  is  ground  down  even 
with  the  backing,  and  the  facing  then  mounted  with  cement. 


1«I 
Bryant  $  method. 

Among  the  most  ingenious  methods  used  in  replacing  facings  is  the 
one  devised  by  Dr.  Emory  A.  Bryant,  of  Washington,  D.  C.  This  con- 
sists of  countersinking  the  old  backing  from  the  lingual  surface;  then 
threading  the  pins  of  the  facing,  and  attaching  it  to  the  backing  by  means 
of  a  corresponding  countersunk  nut. 

The  latter  are  procurable  in  ready-made  form,  as  are  also  the  neces- 
sary instruments  for  doing  the  work,  and  while  this  method  affords  a  se- 
cure means  of  attachment,  the  detail  is  somewhat  exacting  and  requires 
considerable  time. 

It  is  perhaps  more  generally  applicable  to  replacing  facings  on  bicus- 
pids, or  even  molars,  in  bridgework,  than  to  the  anterior  teeth,  because 
the  strength  of  the  attachment  increases,  of  course,  in  proportion  to  the 
thickness  of  the  backing,  which  in  this  particular  region  is  necessarily 
governed  by  the  occlusion,  yet  it  may  often  be  applied  here. 


Ficj.  ISO. 


<L 


In  the  application  of  this  method,  the  remain- 
Bppllcation.  ing    porcelain,    and    projecting    ends    of    the    pins, 

should  be  removed,  the  new  facing  selected,  and  the 
backing  accurately  perforated  for  the  reception  of  the  pins,  as  previously 
indicated ;  after  which  the  facing  should  be  ground  to  the  required  adap- 
tation. 

The  perforations  in  the  backing  are  now  countersunk  from  the 
lingual  surface  with  the  countersinking  reamer  in  right  angle  handpiece, 
until  they  are  suitably  enlarged  to  receive  the  small  end  of  the  nut  and 
admit  of  bringing  it  flush  and  even  with  the  labial  or  buccal  surface  of 
the  backing  (Fig.  150  A.),  care  being  observed  tJiat  it  shall  not  protrude 
to  tJie  least  extent. 

When  this  has  been  accomplished,  J;he  pins  of  the  facing  should  be 
threaded,  first  with  the  large  size  tool,  or  screw-plate,  suul  finally  with 
the  smaller  one;  in  this  procedure  care  must  be  exercised  to  prevent 
twisting  off  the  pins.  The  use  of  a  little  oil  will  preclude  this  and  facili- 
tate the  work. 


I«2 

The  nuts  are  made  of  a  well  alloyed  gold,  corresponding  in  size  with 
the  reamer,  and  are  tapped  to  fit  the  threaded  pins  of  the  facing,  to  each 
of  which  the  respective  nuts  should  be  first  adjusted  to  place,  before  the 
permanent  attachment  of  the  facing  to  the  backing  is  made. 

The  backing  should  then  be  coated  with  cement,  the  facing  placed 
in  position  and  the  nuts  adjusted  to  the  pins  (Fig.  150  B)  (which  may  be 
facilitated  by  a  "holder"),  and  alternately  screwed  to  place  with  the 
wrench,  avoiding  undue  force,  until  both  are  firmly  fixed  in  their  proper 
relation  and  the  attachment  is  secure. 

The  projecting  ends  of  the  nuts  and  pins  should  now  be  ground 
down,  with  small  carborundum  stones,  until  smooth  and  continuous  with 
the  backing,  and  the  surface  subsequently  polished  with  disks.  (Fig. 
150  C) 

The  nuts,  and  a  wrench,  suitable  for  their  adjustment,  are  illustrated 
in  Fig.  150  D. 

The    replacement   of   facings   on  bicuspids   and 
Replacing  Bicuspid      molars,  although  perhaps  most  generally  confined  to 
or  molar  lacings,       bridgework,  will  be  also  considered  in  this  connec- 
tion.    This  is   usually    a    somewhat    more    difficult 
procedure,  because  of  the  increased  thickness  of  the  gold  forming  the 
cusps  and  lingual  contour,  and  surrounding  the  area  where  the  attach- 
ment must  be  secured,  which  usually  precludes  a  projection  of  the  ends 
of  the  pins. 

Where  it  may  not  be  desirable  to  employ  the  Bryant  method,  or 
where  the  same  may  seem  contraindicated,  or  be  impracticable,  the  most 
simple  and  commonly  applied  procedure  is  to  cut  a  countersunk  aperture 
in  the  old  backing  with  drills  and  burs,  of  proportions  sufficiently  large  to 
admit  and  accommodate  both  pins  of  an  ordinary  facing. 

The  facing  should  then  be  selected  and  ground  to  the  required  adap- 
tation, and  the  ends  of  the  pins  bent  somewhat  diverging  from  each 
other,  or  to  present  short  sharp  right  angle  turns,  which  may  be  passed 
into  the  aperture  when  the  facing  is  slightly  inverted,  and  which  will 
hook  over  its  edge  upon  bringing  the  facing  into  proper  position. 

This  will  increase  the  integrity  and  strength  of  the  subsequent  at- 
tachment with  cement,  and  the  same  may  be  further  facilitated  by  serrat- 
ing  or  roughening  the  surface  of  the  backing  with  a  sharp  wheel  or  in- 
verted cone  bur. 

Facing  and  backing  should  now  be  thoroughly  dried,  and  the  mount- 
ing made  with  cement  mixed  fairly  thick,  and  with  an  observation  of  the 
previously  mentioned  details  in  this  connection,  reasonably  permanent 
results  may  be  obtained. 

Where   adequate  mechanical   retention  is  possible,  plastic  amalgam 


Keplacement  of 
facJKd  i'M  Backing. 


183 

may  often  be  used  to  good  advantage,  and  is  sometimes  preferable  to 
cement. 

In  those  cases  where  the  old  backing  has  been 
almost,  or  entirely,  destroyed,  so  that  sufficient  oppor- 
tunity for  securing  adequate  anchorage  for  a  new 
facing,  by  any  of  these  methods,  is  doubtful ;  or 
where  the  cap  and  dowel  have  become  detached  from  the  root,  or  may 
be  removed  without  mutilation  or  destruction,  repair  can  almost  invariably 
be  best  effected  by  cutting  the  remaining  backing  off  close  to  the  base  of 
the  cap  with  a  fine  saw,  excising  forceps,  carborundum  stones  or  files, 
and  attaching  the  facing  and  its  new  backing  by  investing  and  soldering 
in  the  usual  manner. 

The  mechanical  saw  (Fig.  151)  will  usually  be  found  best  adapted 
to  such  purpose,  and  is  an  indispensable  device  to  a  well-equiped  labo- 
ratory. 


fj<l.  I5U 


This  procedure  will  afiford  opportunity  for  securing  the  strongest 
and  most  artistic  results  wherever  the  adaptation  between  cap  and  root 
is  sufficiently  good  to  warrant  the  use  of  the  old  cap,  and  where  this  is 
doubtful,  a  new  crown  should  be  constructed  throughout. 

In  such  instances  the  procedure  should  consist 
Procedure,  in  first  removing  the  remaining  cement  from  the  in- 

terior of  the  cap,  with  burs,  and  then  thoroughly 
cleansing  in  acid.  The  dowel  should  now  be  grasped  firmly  in  a  jeweler's 
pin-vise  (Fig.  152)  (which  is  a  most  useful  instrument  in  this  work), 
and  the  backing  removed  up  sufficiently  close  to  the  base  of  the  crown 
to  offer  no  obstruction  to  the  proper  adjustment  of  the  facing. 

The  cap  should  be  then  placed  in  position  upon  the  root,  and  the 
usual  "bite"  and  impression  taken,  when  the  repair  can  be  made  upon 
the  models  in  accordance  with  the  usual  method  of  construction  from 
this  point  on. 


i84 

Kctttcvittg. 

The  removal  of  this  style  of  crown  may  often  become  necessary  for 
the  purpose  of  replacement  or  substitution,  and  while  the  procedure  may 
be  found  somewhat  difficult  in  those  cases  where  the  attachment  remains 
secure,  it  may  be  effected  by  one  or  the  other  of  the  following"  methods : 


riQ.132. 


The  easiest  and  most  convenient  method,  when- 

Use  Of  ever   applicable,   is    to   first   crush    and   remove   the 

excising  forceps.      facing    if    present,    and    then    grasp    the    remaining 

backing  up  close  to  the  base  of  the  crown,  where 
it  is  thickest,  with  the  beaks  of  a  pair  of  excising 
forceps  (Fig.  153)  (which  is  also  a  most  useful 
instrument),  and  then  gradually  and  slowly 
fracture  the  cement  and  destroy  the  integrity 
of  the  attachment,  by  exerting  a  slight  pressure 
upon  the  handles  and  a  lateral  or  rotary  move- 
ment upon  the  crown. 

The  power  of  the  lever,  in  this  application, 
will  usually  result  in  the  ready  detachment  of 
the  crown  from  the  root,  but  force  should  be 
applied  slowly  and  with  exteeme  care,  in  order 
to  prevent  injury  to  the  peridental  membrane, 
or  the  removal  of  the  root. 

In  the  event  of  loosening  the  root,  because 
of  its  instability,  or  of  the  strength  and  integrity 
of  the  attachment  of  the  crown,  zvhich  will 
ahvays  cause  a  slight  gingival  hemorrhage,  this 
procedure  should  be  at  once  discontinued  before 
injury  has  resulted,  and  another  one  requiring 
less  force  will  be  demanded. 

When  the  above  method 

seems     contraindicated,     or  iKJtl^O' 

proves  ineffective,  or  where 
the  backing  has  been  previously  destroyed  until  no  opportunity  is  afforded 
for  its  application,  the  removal  may  be  facilitated  and  made  easy    and 
devoid  of  danger,  by  first  separating  the  cap  from  the  dowel. 


Separating 
£ap  ana  Eowel. 


i85 

This  may  be  done  by  drilling  through  the  base  of  the  crown  at  a  point 
approximating  the  periphery  of  the  dozvel,  until  the  root  has  been  reached, 
with  a  small  drill  or  round  bur,  and  then  severing  the  cap  from  the  dowel 
with  burs  of  a  larger  size   (Fig.  154). 

When  this  has  been  accomplished,  if  it  is  desirable  to  utilize  the  cap 
again,  it  should  be  worked  loose  and  lifted  off  with  pliers  ;  but  if  no  further 


use  is  to  be  made  of  it,  the  procedure  may  be  facilitated  by  destroying 
the  continuity  of  the  band  with  excising  or  crown  slitting  forceps,  or  a 
small  bur  (  Fig.  155). 

The  remaining  dowel  should  then  be  removed  by  cutting  away  the 
surrounding  cement  with  very  small  round  burs,  until  it  may  be  gripped 
with  strong  small-pointed  pliers,  and  the  entire  length  removed. 


F/<^.  155. 


In  this  procedure,  however,  care  must  be  exercised  to  avoid  per- 
forating the  root,  or  breaking  off  the  dowel  at  a  point  which  will  preclude 
the  removal  of  the  remaining  end. 

The  use  of  the  very  ingenious  instrument  devised  by  Dr.  C.  G. 
Morrell  for  this  purpose  will  be  found  very  convenient,  and  it  is  par- 
ticularly applicable  to  the  removal  of  crowns  or  bridges  when  some 
effort  to  preserve   the   piece   is   desirable.      (See   Fig.   359.) 


18(3 


Another  method,  which  has  the  advantage  of  leaving  the  dowel 
projecting  to  a  considerable  extent  from  the  end  of  the  root,  is  as  fol- 
lows :  The  porcelain  facing  being  absent,  or  having  been  crushed  and 
removed,  a  small  drill  hole  is  made  in  the  cap,  at  the  labial  aspect,  and 


FicjJBG. 


to  one  side  of  where  the  dowel  is  known  to  be  attached.  This  per- 
foration, sufficient  to  slightly  disclose  the  cement,  is  easily  made,  after 
which  the  drill  is  changed  for  a  small  but  sharp  rose  bur.  With  this 
bur  a  groove  is  cut  incisally,  and  alongside  of  the  dowel  about  two-thirds 
of  the  length  of  the  backing.     A  similar  drill  hole  and  groove  is  then 


Fiq.  157. 


cut  on  the  other  side  of  the  dowel,  and  the  two  united  across  at  the  end 
(Fig.  156).  With  a  little  additional  burring  the  cap  and  backing  can 
then  be  removed,  leaving  the  dowel  with  some  of  the  original  backing 
adhering  to  it,  protruding  from  the  end  of  the  root  (Fig.  157),  thus  afford- 
ing considerable  metal  which  may  be  grasped  in  the  pliers.     In  Fig.  156 


i87 

the  backing  is  cut  clear  through,  but  in  a  thick  backing  this  would  not  be 
necessary,  much  less  cutting  serving  to  release  the  dowel.  The  cement 
should  be  burred  away  as  before  indicated,  but  the  removal  of  the  dowel 
is  much  facilitated. 


tk  Pidte  ana  h^m\  V^r^m. 


CHAPTER  X. 

Advantages.       Indications,       Requirements.       Method    of     Construction;     Typical 
Cases;    Root    Preparation;    Six    Anterior     Teeth,     Bicuspids.       Adaptation 
of  Plate,  Adjustment  of  Dowel.     Extensive   Destruction  of  Root: 
Swaging   Plate ;   Impression  of  Root,  Dies,  Dowels.     Con- 
struction upon  Models. 


In  view  of  the  great  variation  of  conditions  presenting,  and  because 
of  the  possible  objections  to  a  band  which  may  be  made  with  reason  and 
consistency  in  some  instances,  and  in  certain  classes  of  cases ;  together 
with  the  advantages  to  be  derived  from  a  close  and  more  or  less  perfect 
adaptation  of  the  base  of  the  crown  to  the  end  of  the  root,  and  the  esthetic 
possibilities  afforded — the  plate  and  dowel  crown  differing  from  the  pre- 
ceding style  by  the  absence  of  a  band,  and  consisting  simply  of  a  plate 
and  dowel  base,  has  a  wide  range  of  application  and  usefulness,  and  is 
somewhat  extensively  employed  in  the  restoration  of  the  ten  anterior 
teeth,  and  even  sometimes  on  the  molars. 

When    the   employment    of    a   band    is    contra- 

JldoaittagCS.  indicated,  or  sejmingly  undesirable,  such  a  style  of 

construction  affords  the  advantage  of  securing  a 
closer  line  of  junction  between  the  crown  and  the  root,  by  burnishing  or 
szvaging  a  thin  metal  base  and  then  adjusting  a  dowel  and  completing 
the  crown  in  the  usual  manner,  than  could  possibly  result  from  grinding 
one  surface  to  conform  closely  with  another,  such  as  becomes  necessary 
in  the  application  of  the  various  fovms  of  ready-made  porcelain  crowns. 
While  the  esthetic  possibilities  thus  afforded  are  also  desirable,  the 
principal  features  lie  in  the  conservation  of  tooth  structure,  the  preserva- 
tion of  the  normal  condition  of  the  gingivae,  and  the  degree  of  perma- 
nency that  must  result  from  obtaining  a  perfect  joint  between  the  crown 
and  both  the  base  and  periphery  of  the  root. 

This  style  of  construction  is  especially  indicated 

Indications.  in  two  general  classes  of  cases,  and  is  applicable  to  a 

third,  as  follows: 


T8g 

In  pathological  conditions  where  any  extensive 
f\tsti  preparation   of  the  remaining  root,    such  as   would 

become  necessary  for  a  band,  is  precluded  because 
of  its  instability,  or  because  of  the  physical  or  nervous  condition  of  the 
patient;  or,  where  a  recession  of  the  gum  from  the  normal  gingival  line 
would  require  the  application  of  a  crown  without  a  band  for  esthetic 
reasons. 

Where  the  decay  and  destruction  of  the  root  is 
Second:  so  extensive  as  to  preclude  the  possibility  of  apply- 

ing a  band, — in  which  conditions,  because  of  the  ex- 
treme shortness  and  consequent  close  proximity  of  the  end  of  the  root  to 
the  border  of  the  alveolus,  no  opportunity  for  securing  an  accurate  adap- 
tation of  a  band  is  aiTorded. 

In  this  class  of  cases  a  crown  may  be  constructed  by  sv/aging  or 
burnishing  a  base  to  a  close  conformation  with  the  surface  and  irregular 
edge  of  the  root,  with  a  degree  of  accuracy  of  adaptation,  and  support 
to  the  root  which  will  offer  a  secure  and  reasonably  permanent  attach- 
ment. 

It  is  also  quite  generally  applicable  and  more  or 

third:  less  extensively  employed  in  those  typical  cases  where 

the  root  is  sufficiently  large  and  strong,    and    free 

from  the  evidences  of  caries  or  disintegration,  as  to  probably  require  no 

support  and  protection,  such  as  the  application  of  a  band  affords. 

Also,  it  is  particularly  applicable  and  perhaps  most  often  the  desir- 
able procedure,  in  restoring  the  crowns  of  partially  developed  teeth  in 
the  mouths  of  young  patients,  because  of  thus  avoiding  any  possible  irri- 
tation to  the  more  or  less  susceptible,  sensitive  and  highly  organized  tis- 
sues in  such  cases. 

The  requirements  of  construction  constitute  se- 
R^dUiremcntS.  curing  a  preparation  of  the  root,  v/herever  sufficient 
tooth  structure  remains,  which  will  mechanically 
prevent  subsequent  displacement  of  the  crown,  and  of  then  securing  adap- 
tation of  the  base  to  both  the  surface  and  periphery  of  the  root,  which  will 
afford  a  firm  seating,  and.  in  so  far  as  possible,  preclude  a  dissolution 
or  disintegration  of  the  cementing  medium,  or  the  subsequent  occurrence 
of  caries. 

While  a  close  observation  and  fulfillment  of  these  requirements  will 
doubtless  make  such  a  result  possible,  the  degree  of  stabilitv  in  the  attach- 
ment will,  of  course,  depend  much,  if  not  entirely,  upon  the  dowel;  which, 
because  of  thus  assuming  a  preponderance  of  the  stress  imposed,  must  he 
properly  adjusted  to  the  canal,  and  of  uniform  and  adequate 
rigidity. 


190 

inctDoa  of  Construction. 

As  the  method  of  construction  for  this  style  of  crown  differs  only 
in  the  details  incident  to  the  preparation  of  the  root,  and  the  adaptation 
of  the  base,  all  reference  to  the  application  of  the  facing  and  the  comple- 
tion of  the  crown,  whether  for  gold  or  porcelain  work,  will  be  purposely 
avoided,  because  the  procedure  from  this  point  on  is  identical  with 
that  which  is  elsewhere  considered  in  connection  with  each. 

In  the  application  of   this    style    of    crown    to 

Cynical  Ca$C$.        typical  cases,  such  as  have  been  considered  in  the 

■first  and  third  classes  of  indications,  and  which  will 

be  confined  mostly  to  the  six  anterior  teeth,  the  first  essential  feature  in 

the  detail  of  construction  is  the  proper  preparation  of  the  basal  surface 

of  the  root. 

In  this  particular  the  requirements  differ  from 

Root  Pr^Piiration.      those  incident  to  the  band  and  dowel  crown,  in  that 

no  peripheral  trinuning  is  necessary,  and  that  the  end 

of  the  root  must  be  so  shaped  as  to  offer  mechanical  resistance  to  the  stress 

imposed. 

In  the  six  anterior  teeth    this    may    be    accom- 

$iX  JllttCflor  t«tb.    plished  by  beveling  the  root  both   labially  and  lin- 

gually  from  a  central  point,  so  that  the  plate,  which 

is  to  form  the  base  of  the  crown,  will  straddle  the  exposed  end,  thus  also 

overcoming  any  tendency  toward  a  possible  rotation  or  displacement  of 

the  crown. 

The  labial  bevel  should  usually  extend  from  the  lingual  edge  of  the 
pulp  canal  to  a  point  sufficiently  far  beneath  the  gum  to  allow  for  the 
thickness  of  the  plate,  and  thus  admit  of  placing  the  neck  of  the  facing 
in  direct  contact  with  the  tissue,  which  adds  to  the  esthetic  effect  by 
making  the  joint  invisible. 

The  lingual  bevel  should  not  extend  quite  to  the  gum  line,  because  of 
the  absence  of  esthetic  requiremients  upon  this  surface,  and  of  the  prob- 
able advantage  in  having  the  joint  exposed  to  view  to  insure  the  accuracy 
of  adaptation,  and  to  the  movements  of  the  tongue  and  action  of  the  secre- 
tions, to  render  it  more  hygienic  or  self-cleansing.     (Fig.  158a.) 

This  preparation  may  be  easily  accomplished  with  flat-edge  carbo- 
rundum stones,  though  the  use  of  the  root  facer  will  facilitate  cutting  the 
root  below  the  gum  upon  the  labial  surface.  Wherever  enamel  is  allowed 
to  remain,  however,  and  no  band  is  employed,  this  instrument  must  be 
revolved  slowly,  and  used  with  extreme  care. 

While  a  similar  preparation  is  usually  desirable 

BiCHSpidS.  for  first  bicuspids,  because  they  are  also  subjected 

to  some  lateral  stress,  it  is  not  so    essential    to   the 


191 

second  bicuspids,  for  the  reason  that  these  teeth  usually  receive  vertical 
stress  mainly,  hence  a  flat  base,  such  as  is  indicated  in  Fig.  53,  is  all  that 
is  necessary,  if  the  size  and  adjustment  of  the  dowel  is  adequate. 

\\'hen  the  desired  preparation  has  been  secured, 
JIdaptation  of  Plate,    a  piece  of  pure  gold,  or  platinum,  as  the  requirements 
of  the  intended  construction  of  the  crown  may  in- 
dicate, about  34  to  36  gauge,  should  be  cut  a  trifle  larger  than  necessary, 
annealed,  and  burnished  to  a  perfect  adaptation  with  the  surface  of  the 
root. 

This  is  easily  accomplished  with  flat  and  round  burnishers,  and  the 
soft  rubber  tip  of  a  lead  pencil  will  also  be  found  useful.  While  the  thin- 
ness and  softness  of  either  pure  gold  or  platinum  will  admit  of  securing 
the  required  adaptation  by  burnishing,  the  same  may  also  be  accomplished 
by  a  primary  swaging,  if  preferable,  though  the  latter  method  is  more 
requisite  in  difficult  cases,  and  will  be  subsequently  considered. 


Ficj.158. 


After  securing  the  proper  adaptation  of  the 
HdjUStment  of  Dowel,  plate,  the  canal  should  then  be  prepared  for  the  re- 
ception of  the  dowel,  and  the  latter  fitted  to  it,  when 
the  plate  should  be  replaced  in  position  and  the  opening  of  the  canal  out- 
lined in  it  with  a  round  or  oval  burnisher.     (Fig.  158  b.) 

The  plate  should  now  be  perforated  with  a  sharp-pointed  instrument 
or  plate  punch,  and  the  dowel  forced  through  the  perforation  until  well 
into  position.  M'hile  the  close  fit  thus  secured  between  plate  and  dowel 
will  usually  sustain  their  relation  while  removing  and  soldering,  if  the 
same  is  doubtful,  the  usual  means  for  sustaining  it,  as  previously  de- 
scribed, may  be  observed. 

The  two  should  now  be  permanently  attached  with  solder  and  then 
again  placed  in  position  on  the  root  and  reburnished,  when  the  surplus 
may  be  trimmed   away   and  the  plate   reinforced  to  prevent  a   possible 


IQ2 

change  of  form  while  taking  the  impression,  and  subsequently  detaching 
from  the  model.     (Fig.  158  C.) 

When  the  plate  is  of  gold,  this  reinforcement  should  be  made  by  flow- 
ing a  thin  layer  of  20  karat  solder  over  the  surface  and  around  the  dowel, 
while  if  a  platinum  plate  has  been  used,  and  a  porcelain  crown  is  to  be 
made,  twenty-live  per  cent  platinum  solder,  or  pure  gold,  may  be  em- 
ployed. 

The  usual  "bite"  and  impression  should  now  be  taken  and  models 
secured,  when  the  facing  should  be  selected  and  ground  to  a  perfect  joint 
with  the  labial  and  cervical  aspect  of  the  plate,  if  it  is  to  be  backed  up  and 
finished  with  gold  (Fig.  158  d),  and  the  crown  then  completed  in  the 
usual  manner,  and  finished  and  mounted.     (Fig.  158  e.) 

€xfen$iDe  Destruction  of  Root. 

In  that  class  of  cases  where  the  root  has  been  more  or  less  extensively 
destroyed  from  disintegration,  or  accident,  and  presents  a  concave  sur- 


Fiq.  159.  c 

face  and  frail  and  irregular  edges  so  deeply  imbedded  beneath  the  gum 
as  to  preclude  the  adaptation  of  a  band,  and  yet  possessing  sufficient 
stability  and  integrity  to  afford  a  reasonably  firm  attachment  for  a  well- 
adapted  crown,  as  has  been  mentioned  in  the  second  class  of  indications, 
the  first  essential  procedure  incident  to  the  construction  of  the  crown  is 
to  tightly  press  away  the  surrounding  soft  tissue  with  temporary  stopping, 
or  gutta  percha,  until  a  free  exposure  of  the  end  of  tbe  root  is  obtained. 

While  this  may  require  two  or  three  sittings,  repeating  the  proce- 
dure at  each,  such  time  will  be  found  to  have  been  well  expended,  when 
it  is  desirable  to  make  an  effort  to  successfully  crown  such  teeth,  because 
of  thus  making  possible  and  facilitating  the  accurate  adaptation  of  the 
plate  to  the  root,  and  the  subsequent  permanent  attachment  of  the  finished 
crown. 

When  the  root  has  been  thus  freely  exposed,  the  irregular  edges 
should  be  ground  down  with  small  stones,  or  root  facer,  until  as  smooth 


193 

and  even  as  possible ;  and  all  decay  then  removed,  after  which  the  re- 
maining root  should  be  thoroughly  disinfected  and  sterilized,  in  order  to 
arrest  any  further  progress  of  caries. 

The  best  means  of  obtaining  the  correct  adaptation  of  the  plate  to 
the  root  will  depend  much  upon  the  condition  presenting,  and  while  the 
required  conformation  may  often  be  obtained  by  burnishing,  a  more  cer- 
tain, and  perhaps  increased,  accuracy  will  not  infrequently  be  secured  by 
swaging. 

To    accomplish    the    swaging,     whenever     such 

Swaging  Plate.        procedure  may  be  indicated,   or  seem  desirable,  an 

accurate  and  well-defined  impression  of  the  edge  and 

surface  of  the  root  must  be  taken,  and  fusible  alloy  dies  m_ade  therefrom. 

The  use  of  pink  base-plate  gutta  percha  affords 
Impression  of  Root,     the  most  simple  and  accurate  means  of  obtaining  a 
well-defined  impression  of  the  end  of  the  root. 
In  the  procedure  this  should  be  cut  into  moderately  small  pieces  and 
carefully  and  slowly  warmed,  on  a  mica  slab  over  a  flame,  or  on  the  elec- 
tric annealer,  until  it  is  plastic,  when  a  quantity  sufficient  to  fill  the  space 
to  be  occupied  by  the  crown  should  be  tightly  packed  with  burnishers 
over  and  against  the  end  of  the  root,  and  in  between  the  adjacent  teeth, 
if  any  be  present. 

This  should  now  be  chilled  with  a  spray  of  cold  water,  and  removed 
(Fig.  159  a),  and  when  sufficiently  accurate,  fusible  alloy  dies  may  be 
obtained  from  it. 

To  obtain  the  dies,  the  impression  should  be  in- 
DiCS.  vested,  with  the  imprint  of  the  root  downward,  in  a 

base  of  plaster  of  proportions  sufficient  to  be  subse- 
quently trimmed  to  admit  of  the  adjustment  of  the  rubber  casting  ring 
(Fig.  159  b).  When  the  plaster  has  become  thoroughly  crystallized,  and 
has  been  thus  trimmed,  it  should  be  placed  over  a  small  flame  and  allowed 
to  heat  slowly  until  the  gutta  percha  may  be  removed  (Fig.  159  c),  when 
the  rubber  ring  should  be  adjusted,  and  the  die,  and  subsequently  the 
counter-die.  secured  with  fusible  alloy.  Or,  the  impression  may  be  taken 
with  hard  modeling  compound,  the  die  made  with  quick-setting  amal- 
gam, and  the  swaging  done  in  a  swaging  device. 

Pure  gold  or  pure  platinum,  as  the  requirements  may  indicate,  of 
the  thickness  of  about  36  gauge,  should  be  now  annealed,  and  swaged, 
after  which  it  may  be  further  adapted  to  the  root  by  burnishing,  as  al- 
ready indicated,  and  the  dowel,  or  dowels,  then  adjusted  and  soldered. 

The  length  and  size  of  the  canal,  or  canals,  in 

Dowels  such  roots  will  indicate  whether  one  or  two  dowels 

should  be  used,  and    as    they    are    generally    much 


194 

shorter  than  usual,  and  the  major  portion  of  the  strength  of  the  attach- 
ment will  depend  upon  the  dowel,  it  is  essential  that  it  should  be  of  ade- 
quate size  and  length  to  thoroughly  fill  the  canal;  hence  the  use  of  two, 
whether  they  may  be  separate  from  each  other,  or  in  contact  and  subse- 
quently united  with  solder,  is  frequently  rec[uired. 

The  relation  between  the  plate  and  dowel,  or  dowels,  should  be  tem- 
porarily secured  in  the  manner  indicated,  and  then  permanently  sustained 
by  soldering,  and  wherever  two  dowels  are  used,  and  particularly  when 
they  are  separated,  an  investment  should  invariably  be  employed. 

^^'hen  they  have  been  soldered,  the  cap  should  be  placed  upon  the 
root  and  the  edge  of  the  plate  readapted  by  burnishing,  in  which  the  use 
of  a  smooth  foot  plugger  in  the  automatic  mallet  will  often  be  found  ad- 
vantageous. 

The  usual  "bite"  and  impression  should  be  then  taken  and  the  crown 
completed  as  the  requirements  may  indicate,  as  illustrated  in  Fig.  i6o. 

While  the  interior  of  such  roots  is  sometimes  previously  filled  with 
cement  or  amalgam,  and  the  plate  then  adapted  to  this  surface  by  burnish- 


Ficj.  160. 


ing,  the  increased  accuracy  obtained  by  swaging  it  to  closely  follow  the 
concaved  surface  of  the  root,  and  the  additional  support  thus  rendered  to 
the  latter  with  a  minimum  quantity  of  cement,  adds  materially  to  the  in- 
tegrity of  the  attachment  between  the  two,  when  subsequently  mounted. 

In  instances  where  it  may  become  necessary  to 

Construction  construct   the  crown  upon  models,   the  most  useful 

Upon  models.  and  accurate  reproduction  of  the  conditions  may  be 
secured  by  first  fitting  a  wooden  dowel  into  the  canal 
and  then  packing  gutta  j)ercha  over  and  around  it,  until  the  impression 
of  the  end  of  the  root  has  been  obtained,  as  indicated. 

When  the  desired  degree  of  accuracy  has  been  thus  secured,  it 
should  be  placed  in  position,  and  a  plaster  impression  then  taken  over  it. 
The  removal  of  the  latter  will  usually  bring  the  gutta  percha  with  it,  but 
if  not,  it  should  be  detached  from  the  root  and  ])laccd  in  its  proper  posi- 
tion in  the  im]jression. 

When  this  has  become  thoroughly  dry,  the  open  ends  may  then  be 
closed  up  with  mouldine,  and  the  impression  filled  with  fusible  alloy. 


195 

After  separating  from  the  plaster,  and  detaching  the  gutta  percha 
and  wooden  dowel,  this  procedure  will  result  in  a  metal  model  with  a 
more  or  less  perfect  reproduction  of  the  root  and  its  canal,  upon  which 
opportunity  is  afforded  for  the  construction  of  the  crown  in  the  manner 
indicated,  and  with  reasonable  accuracy. 

[The  application  of  this  style  of  crown  to  the  molar  teeth  is  perhaps 
confined  more  especially  to  porcelain  work,  but  the  same  general  princi- 
ples should  be  observed  irrespective  of  the  style  of  construction.] 


JiDPlication  of  Ddwel  frowns  mthm  Plate  or  Band. 


CHAPTER  XI. 

Advantages ;    Disadvantages ;    Indications ;    Requirements  ;    Various    Designs ;    Sej 
arable     Dowels,     Inseparable     Dowels,    Comparative    Advantages.     The    Davis 
Crown:      Application,    Mounting,   Repairing,   With  Band   and   Cap;    Accu- 
racy of  Adaptation   Without   Band.    The  Logan  Crown :     Comparative 
Advantages  and  Disadvantages;  Application;  Amounting.  With  Band 
and  Cap.     Advantages ;  Procedure.       Variation     of     Methods : 
Substituting  Separate  Dowel;    Procedure.      Increased    Ac- 
curacy of  Adaptation,   Procedure.       Porcelain     Work. 
The  Brewster  Crown:    Application.    The  "Fellow- 
ship" Crown:  Separable  Dowels.     Repairing. 
Tube    Crowns  :    Application  ;    Procedure. 
Temporary  Crowns:  Indications;  Pro- 
cedure ;    Use    of    Amalgam ;    Use 
of  Vulcanite. 


The  various  styles  of  ready-made  porcelain  crowns  which  are 
designed  to  be  adapted  directly  to  the  root,  without  the  employment 
of  a  band  or  plate,  and  attached  by  means  of  a  dowel,  which  may  be 
either  a  separable  or  inseparable  part  of  the  crown,  will,  in  regular 
sequence,  be  designated  and  considered  under  this  classification. 

While  almost  any  of  the  several  designs  of  this  particular  style  of 
crown  may  be  adapted  with  a  band  and  cap,  or  even  with  a  simple  plate, 
they  are  thus  classified  because  of  being  usually  employed  without  such 
addition,  and  of  being  originally  designed  to  be  so  adapted. 

Although  this  particular  style  of  crown  preceded  all  others  designed 
especially  for  the  anterior  teeth,  they  are  still  used  somewhat  extensively, 
and,  irrespective  of  the  improved  means  for  obtaining  greater  integrity 
and  permanency,  they  doubtless  possess  some  intrinsic  advantages,  and 
still  occupy  a  more  or  less  limited  sphere  of  usefulness  and  serviceability. 

Previous  to  the  individual  construction  of  porce- 

ndoantages.  Iain-faced  crowns,  the  application  of  porcelain  work, 

and  the  present  facilities  for  securing  a  more  per- 
fect adaptation  to  the  root  with  equal  opportunities  for  observing  the 
esthetic  requirements,  as  indicated  in  the  preceding  chapter,  the  advan- 
tages possessed  by  this  style  of  crown  were  particularly  desirable. 

These  constituted  the  ease  with  which  the  finished  crown  might  be 
procured ;  the  absence  of  the  necessity  for  removing  the  enamel   from 


197 

the  periphery  of  the  root ;  the  facility  and  dispatch  with  which  they  might 
be  adapted,  and  the  natural  and  translucent  appearance  which  the  splendid 
forms  and  colors  of  some  makes  afforded. 

While  the  latter  is  always  an  eminently  desirable  feature,  particu- 
larly in  the  restoration  of  the  six  anterior  teeth,  and  gives  to  all  porce- 
lain crowns  of  any  similar  design  a  distinctive  advantage  over  those  in 
which  the  translucency  is  destroyed  by  the  presence  of  a  backing,  the 
former  should  be  so  considered  in  the  application  of  crowns  designed 
to  serve  as  permanent  reproductions,  only  when  such  are  especially  indi- 
cated, and  as  a  means  of  expediency. 

The  principal  features  which  may  be  reason- 
Disadvantages,  ably  regarded  as  disadvantages,  when  such  crowns 
are  adapted  without  band  or  plate,  lie  in  the  diffi- 
culty of  obtaining  a  crown  of  the  same  diameter  as  the  root,  and  of  se- 
curing a  continuous  and  practically  impervious  joint  between  it  and  both 
the  base  and  periphery  of  the  root,  together  with  the  resultant  absence 
of  preventive  means  and  prophylactic  measures  against  the  subsequent 
dissolution  or  disintegration  of  the  cementing  medium  from  the  pene- 
tration of  saliva,  and  the  destruction  of  the  root  by  caries  or  fracture. 

As  the  result  of  a  failure  to  observe  the  higher  requirements  in 
this  connection,  many  roots  have  been  lost  from  caries,  or  fracture,  which 
might  otherwise  have  possessed  greater  integrity  and  usefulness ;  and  it  is 
by  no  means  uncommon  to  see  such  crowns  so  displaced  from  the  stress 
of  mastication,  and  the  inherent  weakness  of  the  dowel,  as  to  effect  a 
disarrangement  of  the  alignment,  and  afford  a  pocket  between  crown 
and  root  which  serves  as  a  receptacle  for  the  accumulation  of  the  products 
of  decomposition. 

In  consequence  of  these  possible  disadvantages 
Indications.  the  application  of  such   crowns   without   a  band  or 

plate,  or  without  observing  some  means  of  securing 
a  more  perfect  and  impervious  joint  than  can  usually  be  obtained  by 
grinding  one  surface  to  fit,  and  approximate  with,  another,  is  usually 
indicated  only  in  those  cases  where  expediency  renders  such  choice  abso- 
lutely necessary ;  or  where,  from  the  instability  of  the  root,  a  recession  of 
the  gum  tissue,  or  other  pathological  conditions,  or  for  pecuniary  reasons 
the  application  of  a  crown  affording  greater  stability  in  the  attachment, 
or  greater  protection  to  the  root,  may  not  seem  warrantable. 

And  even  in  such  instances  their  application  should  usually  be  con- 
fined to  the  six  anterior  teeth,  because  of  the  increased  difficulty  or- 
dinarily encountered  in  adjusting  them  to  the  more  or  less  irregular 
shapes  and  uncertain  canals  of  the  bicuspids  and  molars. 


198 

Conscientiously  considered,  such  crowns  must  usually  be  regarded  as 
temporary  zvork,  in  view  of  the  reasonable  opportunities  for  securing 
greater  permanency. 

Requirements. 

In  the  application  of  any  of  the  various  designs  now  used,  the  same 
esthetic  requirements  as  indicated  in  the  preceding  chapter  prevail,  and 
the  possible  permanency  of  the  crowns  will  naturally  increase  in  proportion 
to  the  degree  of  accuracy  obtained  in  adapting  them  to  a  close  approx- 
imation with  both  the  base  and  peripheral  outline  of  the  root ;  and  much 
of  the  success  attending  such  an  adaptation  will  depend  upon  the  proper 
root  preparation. 

In  the  preparation  of  the  root  for  the  reception 
KOOt  Preparation.      of  such  crowns,  the  removal  of  enamel,  or  peripheral 
preparation  of  any  kind,  becomes  entirely  unneces- 
sary, of  course,  but  the  shape  given  to  the  basal  surface  should  differ 


from  that  indicated  for  the  plate  and  dowel  crown,  because  of  the  in- 
creased difficulty  of  securing  an  adaptation  to  such  a  shape,  hy  grinding. 

With  the  exception  of  the  peripheral  trimming,  the  preparation  pre- 
viously indicated  in  Fig.  50  will  be  found  the  most  favorable  to  the  re- 
quirements of  the  crown,  and  to  the  facility  and  accuracy  with  which  the 
adaptation  may  be  secured. 

This  consists  in  grinding  the  labial  edge  just  beneath  the  gingival 
line,  and  in  allowing  the  lingual  to  project  slightly  beyond  it,  with  the 
basal  surface  assuming  a  smooth  inclined  plane.     (Fig.  161.) 

The  former  admits  of  the  advantages  considered  in  this  connection 
in  the  preceding  chapter,  while  the  latter  greatly  facilitates  the  opportuni- 
ties for  securing  the  desired  and  required  adaptation  of  the  crown  to 
the  root. 


199 
Uarious  Designs. 

Although  numerous  designs  of  this  style  of  crown  have  been  pre- 
sented from  time  to  time,  as  previously  recorded,  only  those  which  are 
now  manufactured  in  good  variety,  and  which  are  more  or  less  extensively 
employed,  will  be  considered.  In  their  consideration  it  becomes  necessary 
to  divide  them  into  two  classes,  because  of  the  variation  in  their  con- 
struction, and  in  the  details  incident  to  their  respective  application.  Such 
variation  mainly  depends  upon  the  possession  of  separable  or  inseparahle 
dowels,  and  causes  them  to  be  classified  accordingly. 

The  feature  of  this  class  of  crowns  embraces  a 
Separable  Dowels,      separable  or  removable  dowel,  which  may  be  previ- 
ously mounted  in  the  root,  and  to  the  projecting  end 
of  which  the  crown  may  be  subsequently  attached.     They  are  designed 
for  the  purpose  of  facilitating  the  adaptation  of  the  crown  to  the  root, 
and  include  the  principles  first  recognized  by  the  Davis  crown. 

This    class    of    crowns    embraces    the    feature 
Inseparable  Dowels,     of  an  inseparable  dowel,  which  is  baked  in  or  other- 
wise securely  attached  to,  the  porcelain,  and  forms 
an  integral  part  of  the  crown,  such  as  the  original  Logan,  Brewster  and 
"Fellowship"  designs. 

While  both  of  these  styles,  and  all  of  these  re- 
^ .  i'  spective   makes   of   crowns,    are    much   used    at   the 

present  time,  and  either  is  capable  of  being  more  or 
less  readily  adjusted  to  the  root,  a  close  study  and  analysis  of  the  com- 
parative advantages  of  the  two  classes  must  result  in  favor  of  those  pos- 
sessing a  separable  or  removable  dowel,  providing,  of  course,  that  ade- 
quate means  are  afforded  for  the  subsequent  attachment  of  the  crown. 

This  is  apparent,  for  the  reason  that  the  opportunities  for  securing 
the  closest  possible  adaptation,  by  grinding,  are  greatly  facilitated  by  the 
temporary  absence  of  the  dowel,  as  its  presence  must  necessarily  afford 
some  obstruction  to  this  procedure,  and  at  least  increase  the  difficulties 
attending  it,  together  with  the  liability  of  weakening  the  dowel,  by 
grinding  it,  during  the  process. 

Cbe  Daois  Crown. 

Of  the  several  designs  of  crowns  possessing  separable  dowels,  the 
Davis  crown,  suggested  by  Dr.  Chas.  H.  Davis,  and  manufactured  by 
the  Consolidated  Dental  [Manufacturing  Co..  was  the  first  one  to  be  em- 
ployed to  any  extent,  or  to  be  made  in  a  sufficient  variety  of  moulds  and 
colors  to  meet  the  requirenienls,  and  it  still  enjoys  quite  an  extensive 
application. 

It    is    an    all    porcelain    crown,    liaving    a    slightly    concaved    base. 


200 

in  the  center  of  which  is  a  depressed  rim,  which  affords  a  rest  for  the 
shoulder  on  the  dowel,  and  a  countersunk  cavity  extending  into  the 
crown  sufficiently  deep  to  accommodate  the  projecting  end  of  the  dowel. 

The  dowel  is  proportionate  with  the  size  of  the  crown;  slightly 
tapered ;  corrugated  throughout  its  entire  length  to  afford  increased  at- 
tachment to  the  cementing  medium ;  has  one  flattened  side  to  prevent  the 
possibility  of  rotation,  and  a  shoulder  which  adapts  itself  to  the  depressed 
rim  for  its  accommodation  in  the  crown,  and  is  made  of  German  silver 
alloy  for  the  purpose  of  obtaining  greater  inherent  strength  and  rigidity 
than  is  possessed  by  platinum.     (Fig.  162.) 

When  the  proper  selection  has  been  made,  the 

Jlpplication.  primary    rough    grinding    may    be    done    upon    the 

model    if    the    outline    of    the    root    is     sufficiently 

accurate,  but  the  final  adjustment  to  the  desired  adaptation  should  be 


Ficj.162. 


Fia.163. 


made  directly  upon  the  root  itself.  This  should  be  accomplished  with 
carborundum  stones  in  the  engine,  and  when  sufficiently  accurate  the 
ground  surfaces,  excepting  the  base,  should  be  then  nicely  polished  with 
disks. 

The  canal  should  now  be  prepared  for  the  reception  of  the  dowel, 
and  the  latter  fitted  closely  to  it;  in  some  roots  it  may  become  necessary 
to  shorten  it  somewhat  from  the  apical  end.  When  thus  primarily  fitted, 
it  should  be  placed  in  position  in  the  crown  and  temporarily  sustained 
with  wax  until  the  two  may  be  adjusted  to  position  on  the  root.  (Fig. 
163,  A.)  This  may  necessitate  a  slight  enlargement  of  the  basal  portion 
of  the  canal,  or  possibly  the  bending  of  the  dowel,  until  the  adjustment  of 
the  crown  to  its  proper  relation  with  the  root  is  obtained,  after  which 
the  crown  and  dowel  may  be  permanently  mounted.     (Fig.  163,  B.) 


20I 

In  mounting,  all  particles    of    wax    should    be 
IflOUntinfi,  thoroughly  removed  from  the  crown  and  dowel,  and 

the  root  rendered  aseptic  and  dry,  when  the  attach- 
ment of  the  latter  to  both  crown  and  root  may  be  made  simultaneously 
with  cement,  or  if  it  is  preferable  to  use  gutta  percha,  the  dowel  should 
be  first  fixed  in  the  crown  with  cement,  and  attachment  to  the  root  made 
with  gutta  percha. 

One  of  the  most  important  advantages  possessed 
Kcpairins.  by  this  style  of  crown  is  the  ease  and  facility  with 

which  repair  may  be  effected  in  the  event  of  subse- 
quent fracture. 

In  such  instances  the  dowel  need  not  usually  be  disturbed,  as  its  pro- 
jecting end  will  afford  ample  opportunity  for  the  retention  of  a  new 
crown,  after  the  removal  of  the  remaining  cement,  and  the  necessary 
adaptation  has  been  secured  by  grinding.  These  crowns  may  also  often  be 
found  applicable  and  useful  in  the  repair  of  the  Logan,  and  other  styles 
of  crowns,  where  no  backing  is  used,  and  the  projecting  end  of  the  dowel 
remains  sufficiently  long  to  afford  adequate  retention  and  resistance. 

When   it  may  seem   desirable    to    employ    the 
Ulltl)  Band  and  0ap.     band  and  cap,  in  the  adaptation  of  this  crown,  and 
thus  add  to  its  possible  permanency  by   supplying 
means  for  the  protection  of  the  root,  it  may  be  accomplished  with  ease. 

In  their  application  in  conjunction  with  band  and  cap,  the  root 
should  be  prepared  and  the  band  fitted  in  exact  accordance  with  the  prin- 
ciples previously  outlined  in  connection  with  the  band  and  dozvel  croivn. 
When  the  band  has  been  thus  fitted  and  trimmed  to  the  proper  width, 
and  the  root  ground  down  to  evenly  approximate  its  edge,  as  indicated  in 
Fig.  125,  B,  the  crown  should  be  selected  and  ground  to  a  close  confor- 
mation with  the  basal  surface  of  the  root,  as  well  as  its  peripheral  outline. 
The  dowel  should  then  be  temporarily  adjusted  to  the  crown  and 
fitted  to  the  canal,  until  the  crown  may  assume  its  proper  relation.  A 
plate  of  pure  gold,  32  gauge,  should  now  be  perforated  for  the  dowel, 
placed  in  position  on  the  crown,  and  trimmed  to  follow  its  outline,  with 
an  allowance  of  about  1/32  of  an  inch  surplus  around  the  entire  circum- 
ference. 

After  annealing  this  plate,  it  should  be  again  placed  in  position  on 
the  crown,  and  both  adjusted  to  the  root,  with  the  band  in  place.  A  de- 
gree of  accuracy  in  the  adaptation  of  the  plate  to  the  root,  crown,  and 
edge  of  the  band  may  be  obtained  by  placing  a  piece  of  soft  wood  against 
the  end  of  the  crown,  and  gently  tapping  it  with  a  mallet,  and  then  hold- 
ing firmly  and  burnishing  the  surplus  edge  of  the  pure  gold  plate  up 
ticht  as'ainst  the  band. 


202 


When  this  has  been  accomplished,  the  crown  should  be  removed, 
and  the  pure  gold  plate  placed  in  its  proper  relation  to  the  band,  which 
has  been  made  possible  by  the  burnishing  of  this  surplus  edge,  and  the 
two  then  united  with  20  karat  solder. 

When  the  cap  has  been  formed  by  the  union  of  the  band  and  plate, 
and  the  surplus  and  excess  edge  finished  down  smooth  with  stones  and 
disks,  it  should  be  adjusted  to  position  on  the  crown  (to  which  the  dowel 
still  remains  temporarily  attached)  and  securely  united  with  wax. 

The  interior  of  the  cap  should  now  be  filled  with  investment  ma- 
terial, or  plaster,  as  indicated  in  Fig.  127,  in  order  to  securely  sustain 
their  relation  while  soldering.  After  this  has  become  sufficiently  hard- 
ened, the  crown  may  be  easily  detached  by  slightly  heating  it  over  a  flame 
until  the  wax  melts,  when  the  dowel  should  be  united  to  the  cap  by  filling 
in  the  space  around  the  shoulder  with  20  karat  solder. 

The  cap  may  now  be  finished  and  polished,  and  then  permanently 
attached    to    the    root,    when     the    crown    may    be     placed     in    posi- 


Ficj .  164-. 


tion,  and  if  too  long,  because  of  the  thickness  of  the  pure  gold  between 
it  and  the  root,  the  incisal  end  should  be  ground  until  the  length  is  cor- 
rect and  the  crown  then  subsequently  mounted  with  cement.  (Fig. 
164.) 

While  the  floor  may  be  attached  to  the  band  in  the  ordinary  man- 
ner, without  observing  this  detail,  and  the  proper  relation  between  the 
parts  subsequently  secured,  tnis  procedure  is  warrantable  and  preferable 
because  of  the  accuracy  and  the  conservation  of  tooth  structure  thus  ob- 
tained, as  otherwise  the  canal  may  need  to  be  much  enlarged  to  admit  of 
placing  the  crown  in  its  proper  position  and  relation. 

A  method  of    securing    a    preservation    of    the 
JHccuracy  of  Jidaptation  root,  and  a  degree  of  accuracy  in  the  adaptation  of 

UJitbOUtBand.         these  crowns,  without  a  band  or  cap,  which  seems 
quite  ])ractical  and  applicable  to    many    cases,    has 
been  suggested  by  Dr.  J.  R.  Owens,  of  Cleveland,  Ohio. 


203 

In  this  method  the  basal  end  of  the  canal  is  enlarged  as  much  as  is 
consistent  with  the  strength  of  the  remaining  edge  of  the  root,  and  then 
somewhat  countersunk.     (Fig.   165,  A.) 

The  crown  is  then  adjusted  to  its  proper  adaptation  by  grinding,  and 
the  dowel  subsequently  fitted  until  admitting  of  the  correct  adjustment 
of  the  crown,  when  the  dowel  should  be  mounted  in  the  constricted  por- 
tion of  the  canal  with  cement. 

The  surplus  cement  flowing  into  the  countersunk  cavity  should  be 
removed  and  the  latter  then  filled  with  amalgam.  (Fig.  165,  B.)  While 
this  remains  plastic,  the  crown  should  be  placed  in  position  and  gently 
forced  to  its  proper  adaptation  with  a  piece  of  soft  wood  and  small 
mallet.  The  excess  amalgam  is  then  trimmed  away,  until  a  smooth  joint 
between  crown  and  root  remains,  when  the  crown  should  be  gently  re- 
moved and  afterward  permanently  attached  with  cement.     (Fig.  165,  C.) 

The  advantages  claimed  for  this  method  are  the  protection  afforded 


to  the  end  of  the  root  by  the  amalgam,  and  the  accuracy  of  the  adapta- 
tion between  crown  and  root  which  is  facilitated  by  its  manipulation  while 
in  the  plastic  state.  Its  application,  however,  is  necessarily  confined  to 
good,  strong  roots,  and  while  the  How  "screw-post"  is  used  by  the 
advocate,  as  illustrated,  the  dowel  of  the  Davis  crown  will  doubtless 
answer  as  well. 

Cbc  Codan  €rown. 

Of  the  various  crowns  with  fixed,  or  inseparable  dowels,  the  Logan 
crown,  originally  designed  by  Dr.  M.  L.  Logan,  and  manufactured  by 
the  S.  S.  White  Dental  Mfg.  Co.,  is,  because  of  the  almost  unlimited 
variety  of  splendid  forms  and  colors  in  which  it  is  made,  probably  the 
most  generally  employed  and  universally  adaptable. 

The  crown  is  made  wuth  a  slight  groove  or  depression  in  its  base, 
immediately  surrounding  the  dowel,  thus  forming  an  elevated  rim 
around  the  edge  which  facilitates  the  adaptation,  and,  when  not  entirely 


204 

obliterated  by  grinding,  affords  increased  strength  to  the  attachment  by 
admitting  of  the  presence  of  a  greater  quantity  of  the  mounting  material. 
The  dowel  is  of  platinum  and  is  baked  into  the  body  of  the  crown. 
It  is  flattened  and  tapering  in  shape,  and  adjusted  in  the  crown  with  the 
greatest  diameter  placed  labia  and  hucco-lingually,  or  in  line  with  the 
direction  in  which  the  greatest  stress  is  usually  imposed ;  and  a  slight 
corrugated  depression  in  each  side  aids  the  attachment  of  the  mounting 
material.     (Fig.  i66.) 

While  this  form  of  dowel  is  based  upon  theo- 
Comparative  retically  scientific  principles,   objectionable  features 

Jidoantages  and  of  some  importance  contra-indicate  its  too  general 
DisadPantages.  application,  and  detract  from  its  practicability. 
These  constitute  the  possible  weakening  of  small 
roots  by  the  enlargement  of  their  canals  to  the  extent  necessary  to  ac- 
commodate the  greatest  diameter  of  the  dowel ;  the  possibility  of  its 
bending  under  the  application  of  stress  in  the  line  of  its  smallest  diameter, 
and  the  inherent  weakness   of  a  platinum  dowel  which  is  further  an- 


M 


Ficj.  166. 

nealed  to  its  softest  form  by  being  subjected  to  the  high  degree  of  heat 
necessary  to  fuse  the  porcelain. 

In  many  cases  this  required  destruction  of  the  root  may  leave  it 
so  weakened  as  to  be  more  or  less  easily  fractured,  if  no  band  is  em- 
ployed, which  is  not  an  uncommon  occurrence ;  and  the  lack  of  rigidity 
in  the  dowel,  particularly  in  its  lateral  dimensions,  affords  opportunity 
for  it  to  bend  under  stress  in  this  direction,  and  thus  admit  of  the  dis- 
placement of  the  crown,  which  tendency  or  possibility  may  not  always 
be  overcome  by  the  close  approximation  of  the  crown  to  the  adjacent 
teeth. 

In  such  cases,  and  especially  where  the  latter  is  not  possible,  un- 
less extreme  care  be  taken,  the  employment  of  a  crown  possessing  such 
a  dowel  may  be  contraindicated,  and  the  application  of  one  with  a  more 
round  and  rigid  dowel  may  be  found  more  serviceable. 

In  the  application  of  the  Logan  crown  the  root 

Hppllcatiin.  '^hould  be  prepared,  a  model  secured,  and  the  selec- 

tion made  in  accordance  with  the  previously  men- 
tioned requirements  for  this  general  style  of  crown. 


205 

A  more  accurate  selection  of  the  crown  for  the  individual  case  may 
be  greatly  facilitated  by  preparing  the  canal  after  shaping  the  root,  and 
then  adjusting  a  temporary  dowel  of  wood  or  metal,  allowing  it  to  pass 
well  into  the  canal  and  to  extend  down  to,  or  near,  the  incisal  end  of 
the  adjacent  teeth.  (Fig.  167.)  The  end  of  an  ordinary  wooden  tooth- 
pick will  answer  this  purpose  nicely,  and  when  so  adjusted,  a  modeling 


FJcj.  167, 

compound  impression  should  be  taken  with  it  in  position. 

In  removing  the  impression,  the  temporary  dowel  should  remain 
firmly  embedded  in  it,  or  be  subsequently  so  placed,  and  the  model  made. 

The  removal  of  the  dowel  from  the  model  will  leave  an  outline  of 
the  canal,  and  indicate  its  size,  and  position,  in  relation  to  the  root,  all 
of  which  will  be  found  decidedly  convenient  in,  and  advantageous  to, 
the  selection  of  the  crown,  because  of  the  facility  with  which  it  may  be 
readily  adjusted  to  place.     (Fig.  168.) 


Ficj.168. 


While  the  final  adaptation  of  the  crown  should  always  be  made  di- 
rectly upon  the  root,  the  above  procedure  will  be  found  additionally  ad- 
vantageous if  the  impression  is  taken  in  plaster,  and,  after  drying  thor- 
oughly, then  filled  with  fusible  alloy.  This  affords  an  accurate  and 
comparatively  indestructible  model  containing  the  outline  of  the  base  of 
ihe  root,  and  a  reproduction  of  the  canal ;  and  the  crown  may  be  selected, 


206 

and  primarily  ground  to  a  fairly  accurate  adjustment  upon  it,  during  the 
absence  of  the  patient. 

The  grinding  to  the  proper  adaptation  should  be  accomplished  with 
small  flat-edge  carborunduni  stones,  in  the  engine,  and  care  must  be 
observed  to  avoid  cutting  into  the  dowel,  or  weakening  its  attachment 
to  the  porcelain.     (Fig.  169.)     The  use  of  curved  stones,  suggested  by 


r-iq  .  169. 

]\Ir.  Robert  Brewster,  will  be  subsequently  mentioned  (Page  214)  and 
may  be  found  useful. 

In  the  final  adaptation  of  the  crown,  the  use  of  small  disks  of  carbon 
paper,  perforated  so  as  to  slip  over  the  dowel  and  rest  against  the  base, 
with  the  carbon  side  placed  next  to  the  porcelain,  will  be  found  service- 
able in  securing  a  close  approximation.     (Fig.  170.) 

In  the  use  of  such  disks,  as  the  crown  is  pressed  to  place,  the  points 
of  contact  between  it  and  the  root  will  be  designated  by  a  black  mark 


/vy.  no. 

on  the  porcelain,  and  the  grinding  at  such  points  should  be  continued 
until  the  entire  base  thus  indicates  a  uniform  contact. 

The  requirements  of  peripheral  approximation  and  occlusion  should 
now  be  observed  with  care  not  to  destroy  the  integrity  between  crown 
and  dowel,  and  when  the  adaptation  has  been  completed,  any  surfaces 
of  the  porcelain  which  have  been  ground,  excepting  the  base,  should 
be  nicely  smoothed  and  polished  with  disks,  and  the  crown  then 
mounted. 


207 

While  many  methods  of  mounting  this  style  of 
mounting.  crown  are  advocated,  and  the  subject  in  general  will 

receive  subsequent  consideration,  the  permanency  of 
the  attachment  by  any  method  will,  of  course,  depend  much  upon  the 
accuracy  of  the  adaptation.  Where  the  joint  is  close  enough  to  be  ren- 
dered practically  impervious,  either  cement  or  gutta  percha  may  be 
used,  as  is  the  practice,  and  at  the  discretion  of  the  operator. 

The  indications  for  the  use  of  gutta  percha  increase,  however,  in 
proportion  to  the  inaccuracy  of  the  adaptation,  and  the  two  materials 
may  be  combined  to  advantage  if  desirable.  In  this  procedure  a  disk 
of  the  ordinary  pink  base-plate  gutta  percha  should  be  cut  a  trifle  larger 
than  the  base  of  the  crown,  and  then  perforated  to  slip  over  the  dowel. 
The  latter  should  now  be  slightly  roughened  with  a  sharp  instrument, 
and  both  it  and  the  base  of  the  crown  then  moistened  with  oil  of  cajaput 
or  any  solvent,  and  the  gutta  percha  disk  adjusted  to  position. 

It  should  then  be  placed  on  the  electric  gold  annealer,  or  on  a  mica 
slab,  over  a  flame,  and  slowly  heated  until  the  gutta  percha  becomes 
plastic,  when,  after  moistening  the  root  with  water  to  prevent  adhesion, 
the  crown  may  be  forced  to  place  with  enough  pressure  to  mould  the 
gutta  percha  to  it,  and  to  the  root,  and  to  fill  the  intervening  space. 

While  the  crown  is  now  held  firmly  in  place,  the  surplus  should  be 
trimmed  away  around  the  joint  with  a  sharp,  warm  instrument,  after 
which  it  should  be  removed  and  again  placed  upon  the  heating  apparatus, 
until  the  root  has  been  dried,  and  the  base  then  moistened  with  the 
solvent,  when  it  may  be  mounted  with  cement  in  the  ordinary  manner. 

A  similar  procedure  is  indicated  in  the  use  of  gutta  percha  alone. 

Ulitt)  Bana  and  €ap. 

Several  methods  of  employing  the  Logan  crown  in  combination  with 
a  band  and  cap  have  been  suggested  as  a  means  of  obtaining  greater 
permanency  in  their  application ;  and  when  so  adapted  this  or  almost  any 
of  the  various  forms  of  such  crowns  possesses  advantages  which  place 
them  next  in  rank  to  porcelain  work. 

Such   advantages    constitute   not   only    the    in- 
Jldoantascs.  creased  integrity  of  the  attachment,  and  preserva- 

tion of  the  root,  but  include  the  esthetic  possibilities 
which  may  be  obtained  in  the  translucent  and  natural  appearance  af- 
forded by  an  all  porcelain  crown  devoid  of  the  presence  of  any  backing. 

Of  the  several  methods  advocated  for  so  adapt- 
ProccdWK.  ing  this  style  of  crown,  a  modification  of  the  one  de- 

vised by  Dr.  J.  G.  Hollingsworth  will  be  found  to  be 
the  most  generally  applicable  and  universally  practicable. 


205 


This  consists  in  preparing  the  root  as  previously  indicated  in  con- 
nection with  the  ''band  and  dowel"  crown  and  the  Davis  crown  with  a 
band,  and  in  fitting  the  band  and  constructing  the  finished  cap  in  the 
same  manner  as  prescribed  for  the  former. 

The  crown  should  be  selected  in  accordance  with  the  details  indi- 
cated, and  this  may  be  observed  either  before  or  after  the  adjustment 
of  the  cap.  In  grinding  it  to  the  proper  adaptation,  however,  the  cap 
should  be  laid  aside,  and  the  adjustment  made  directly  to  the  root,  in 
which  procedure  the  original  form  of  the  base  of  the  crown  is  entirely 
changed,  and  it  is  only  necessary  to  observe  accuracy  along  the  labial 
edge.     (Fig.  171,  A.) 


When  a  moderately  accurate  adaptation  of  this  surface  has  been  se- 
cured, together  with  an  observation  of  the  remaining  requirements,  the 
cap  should  be  placed  in  position  on  the  root,  perforated  to  receive  the 
dowel,  and  the  Unal  adjustment  then  made  zvith  it  in  place. 

When  the  required  adaptation  has  been  thus  obtained,  the  base  of 
the  crown  should  be  further  ground  away  on  the  lingual  and  approximal 
edges  until  an  adequate  V-shapcd  space  exists  between  this  portion  of  it 
and  the  cap.  The  space  should  be  large  enough  to  admit  of  being  subse- 
quently filled  with  solder,  by  which  means  the  crown  and  cap  are  per- 
manently attached,  but  should  be  no  larger  than  necessary  to  facilitate 


209 

this  procedure,  because  of  the  possible  weakening  of  the  attachment  of 
the  dowel  in  the  porcelain. 

The  perforation  of  the  cap  should  be  made  with  care  to  have  the 
dowel  Ht  closely  into  it,  as  a  preservation  of  the  accurate  relation  be- 
tween crown  and  cap,  and  the  facility  with  which  a  strong  union  be- 
tween them  may  be  effected,  will  depend  much  upon  such  a  relation.  In 
the  event  of  making  too  large  a  perforation,  an  additional  disk  of  thin 
gold  or  platinum  may  be  more  accurately  adjusted  to  the  dowel,  bur- 
nished to  place  on  the  cap,  and  separately  soldered  in  its  proper  position, 
thus  overcoming  any  possible  difficulties  in  this  connection. 

The  crown  should  now  be  backed  up  with  a  disk  of  platinum,  about 
36  gauge,  which  should  be  properly  perforated,  annealed,  and  closely 
burnished  to  place.  In  trimming  it  to  follow  the  outlines  of  the  base  of 
the  crown,  a  slight  lingual  extension  (Fig.  171,  B)  should  be  allowed  to 
remain,  for  the  purpose  of  engaging  in  the  investment  material,  and  thus 
retaining  the  backing  in  close  proximity  with  the  porcelain  during  the 
process  of  soldering  If  this  precaution  is  not  observed,  the  backing 
will  invariably  be  drawn  away  from  the  base  of  the  crown,  as  a  result  of 
the  shrinkage  of  the  solder,  thus  diminishing  the  strength  of  the  union, 
and  affording  an  unhygienic  joint. 

A  backing  of  pure  gold  might  also  be  used  instead  of  platinum,  but 
the  extreme  thinness  necessary  to  admit  of  carrying  the  porcelain  well 
up  to  the  gingival  line  would  only  introduce  the  possibility  of  fusing  it 
during  the  process  of  filling  this  small  space  with  solder. 

When  the  backing  has  been  adjusted,  it  should  be  attached  in  posi- 
tion on  the  crown  with  melted  adhesive  wax  (Fig.  171,  C),  and  the  re- 
lation between  crown  and  cap  then  secured  on  the  root  (Fig.  171,  D), 
with  the  same  material.  To  accomplish  this  with  accuracy  and  facility, 
the  cap  should  be  placed  in  position  on  the  lOOt,  kept  perfectly  dry,  a  little 
adhesive  wax  melted  on  the  backing  around  the  dowel,  and  the  crown 
then  quickly  carried  to  place  in  its  relation  to  the  cap. 

If  the  adhesive  properties  of  the  wax  are  not  destroyed  by  the  pres- 
ence of  moisture,  and  it  is  sufficiently  heated  to  admit  of  the  proper  ad- 
justment of  the  crown,  the  relation  will  be  securely  sustained,  and  crown 
and  cap  may  be  safely  detached  from  the  root  with  a  small  pointed  ex- 
cavator passed  around  the  edge  of  the  band. 

The  remaining  space  in  the  joint  should  then  be  completely  filled 
with  wax  (Fig.  171,  E),  and  the  crown  invested.  Previous  to  investing, 
the  lingual  extension  of  the  backing  should  be  bent  over  tozvard  the 
porcelain  zvitJwut  overlapping  upon  it,  until  it  may  be  so  engaged  in  the 
investment  material  as  to  be  held  in  place,  yet  offering  no  impediment 
to  the  soldering. 


2IO 

When  the  investment  has  crystalHzed,  it  should  be  trimmed  down 
until  as  small  as  possible,  to  possess  sufficient  strength  to  hold  the  parts 
together.  The  wax  should  now  be  removed,  and  the  joint  between  cap 
and  backing  then  freely  exposed,  so  as  to  admit  of,  and  facilitate  being 
filled  flush  with  solder  (Pig.  171,  F.)  The  case  should  now  be  fluxed, 
heated  thoroughly,  and  the  space  then  filled  with  18  karat  solder. 

In  soldering  such  crowns,  it  must  be  remembered  that  the  porcelain 
contains  a  large  mass  of  platinum,  hence  it  becomes  necessary  to  first 
heat  the  porcelain  well,  in  order  to  prevent  the  occurrence  of  a  fracture. 

In  filling  the  joint,  the  solder  should  be  cut  in  small  pieces,  and 
each  one  of  these  consecutively  applied  and  fused,  to  assure  its  pene- 
tration to  the  full  depth;  and  a  secure  attachment  to  the  dowel,  which, 
being  covered  with  investment  material,  and  being  most  remote  from 
the  exposed  surfaces,  is  in  consequence  the  most  diffi.cult  to  heat  thor- 
oughly. 

This  occasionally  accounts  for  a  failure  to  unite  the  crown  to  the  cap, 
and  in  the  event  of  such  an  accident  their  union  may  be  subsequently  ef- 
fected by  again  investing,  leaving  only  the  interior  of  the  cap  and  the 
dowel  exposed,  and  attaching  with  a  minimum  of  solder  at  the  point  of 
junction  between  the  two. 

The  contouring  of  the  solder  to  a  flush  smooth  surface  may  be  some- 
what facilitated  by  cutting  small  triangular  pieces  of  platinum  or  gold 
foil,  or  thin  plate,  and  adapting  them  to  the  approximal  sides  of  the  wax 
in  the  joint,  before  investing,  thus  forming  a  matrix  for  the  solder. 

When  the  soldering  has  been  completed  and  the  cap  becomes  an  in- 
tegral part  of  the  crown,  it  should  be  finished  and  polished  as  usual  (Fig. 
171,  G),  and  then  mounted. 

Uariation  of  methods. 

Several  other  methods  of  securing  additional  stability  in  the  applica- 
tion of  such  crowns  are  employed,  and  at  least  two  of  them  may  often  be 
used  to  advantage.  These  consist  in  excising  the  original  doivel  and 
replacing  it  with  a  separate  one;  and  in  burnishing  or  szvaging  a  thin 
plate  to  the  basal  end  of  the  root  and  attaching  it  to  the  crown  and 
dowel,  as  a  means  of  securing  a  more  perfect  adaptation  without  the  use 
of  a  band. 

Cases  not  infrequently  present  where  it  may  be 
Substituting  difficult  to  secure  a  proper  adjustment  of  a  fixed- 

Separate  Dowels.       dowel  crown,  because  of  the  constricted  size,  or  un- 
favorable location  of  the  canal ;  or  the  position  or 
shape  of  the  root.    In  such  instances  the  accomplishment  of  good  results 
with  the  use  of  this  style  of  crown  may  occasionally  indicate,  or  even 


211 

necessitate,  the  excision  of  the  original  dowel,  and  the  employment  of  a 
separate  one. 

When   this   procedure   seems   required,   the   cap 

Pro«dore.  should   be   constructed   as   usual,    and    an   ordinary 

platino-iridium  dowel  fitted  to  the  canal  and  soldered 

to  it,  allowing  but  a  shcrt  projecting  end  to  extend  beyond  the  floor  and 

toward  the  porcelain,  so  as  to  ofifer  no,  or  a  minimum,  obstruction  to  the 

subsequent-  adjustment  of  the  crown. 

A  suitable  crown  should  be  then  selected  and  its  dowel  cut  ofT  at  a 
point  about  1/16  of  an  inch  from  the  base,  when  it  may  be  ground  to  the 
proper  adaptation,  as  further  indicated  in  the  preceding  method.  It 
should  then  be  backed  up  in  a  similar  manner,  excepting  that  the  backing 
may  be  trimmed  to  follow  the  entire  outline  of  the  base  of  the  crown, 
and  separately  invested,  so  as  to  afford  a  full  exposure  of  the  surface 
of  the  backing  (Fig.  172,  A).  When  properly  heated,  this  may  be  se- 
curely  attached  to  the  short  projecting  end  of  the  dowel  with  solder. 


F/cj.m. 


The  proper  relation  of  the  crown  to  the  cap  (Fig.  172,  B)  may  now 
be  secured  and  sustained  with  adhesive  wax,  and  the  parts  removed,  in- 
vested and  soldered,  as  indicated.  The  finished  crown  is  illustrated  in 
Fig.  172,  C. 

As  the  degree  of  strength  obtained  in  the  union  of  the  crown  with 
the  cap  and  dowel  will  depend  much  upon  the  length  of  the  projecting 
end  of  each  dowel,  and  naturally  increase  in  proportion  thereto,  this  pro- 
cedure should  be  confined  to  extreme  cases,  or  to  those  wherein  the 
length  of  the  crown  may  admit  of  a  sufficient  exposure  of  the  ends  of 
the  dowels  to  insure  a  degree  of  integrity  in  the  finished  crown. 

A   method   of   securing   increased   accuracy   in 
Tncrcascd  Accuracy     the  adaptation  of  the  crown  to  the  root,  which  is 
Of  Adaptation.         applicable  in  many  instances  where  it  is  not  desir- 
able to  employ  a  band,  was  perhaps  origmally  sug- 
gested by  Dr.  Gordon  White,  of  Nashville,  Tenn. 


212 

This  consists  in  shaping  the  root,  adapting  the  crown,  and  chang- 
ing its  original  form,  as  previously  described. 

In  the  procedure  incident  to  the  employment  of 
Procedure.  this  method,  a  disk  of  platinum  foil,  about  No.  40 

or  50,  is  annealed,  perforated  for  the  dowel,  and 
burnished  to  a  close  adaptation  to  the  base  of  the  crown,  after  the  latter 
has  been  properly  ground,  as  indicated  (Fig.  173,  A).  A  second  disk 
is  then  cut  somewhat  larger  than  necessary,  to  cover  the  end  of  the  root, 
and  closely  adapted  to  it,  thus  forming  a  V-shaped  space  between  the 
two  surfaces  of  metal  which  is  subsequently  filled  with  solder,  in  the 
manner  previously  outlined.     (Fig.  173,  B.) 

The  first  disk,  which  forms  a  backing  for  the  crown,  should  have  a 
slight  lingual  extension  for  the  purpose  of  sustaining  its  close  proxim- 
ity with  the  porcelain  while  soldering;  and  the  second  disk,  which  is 
adapted  to  the  base  of  the  root,  should  possess  a  slight  surplus  on  the 


lingual  surface,  which  may  be  slit  and  burnished  up  over  this  portion  of 
the  root,  thus  resulting  in  the  additional  support  of  a  partial  band. 

In  securing  a  proper  and  close  adaptation  of  each  to  their  respec- 
tive positions,  the  first  disk  should  be  placed  in  position  on  the  crown, 
burnished,  and  trimmed,  and  then  attached  to  the  dowel  with  adhesive 
wax.  A  sufficient  quantity  of  the  latter  to  a  little  more  than  fill  the 
space  between  crown  and  root  should  then  be  placer^  over  this,  and  the 
second  disk  adjusted  to  position  on  the  wax  and  attached  by  touching 
it  with  a  hot  instrument.  The  wax  should  then  b^^  chilled  with  cold 
water,  the  crown  and  disks  placed  in  position  on  the  root,  and  force 
enough  applied  with  a  piece  of  wood  and  small  mallet  to  carry  it  well 
to  place,  which  will  szvage  the  second  disk  to  a  close  conformation  with 
the  base  of  the  root,  if  enough  wax  is  present. 

The  whole  should  then  be  removed  and  the  surphm  wax  trimmed 
down  flush  with  the  crown.  The  second  disk  may  now  be  trimmed  to 
closely  follow  the  outline  of  the  root,  excepting  upon  the  lingual,  which 


213 

portion  may  be  slit,  as  suggested,  and  burnished  up  over  this  surface  of 
the  root  upon  the  replacement  of  the  crown.     (Fig.  174.) 

When  this  has  been  accomplished,  it  should  be  removed,  and  in- 
vested, and  soldered,  with  an  observation  of  the  previously  mentioned 
requirements  and  precautions  in  this  connection,  and  the  finished  crown 
is  illustrated  in  Fig.  173,  C. 

In  roots  possessing  an  irregular  outline  or  concave  base,  this,  or  a 
similar,  procedure  may  be  found  advantageous ;  and  the  disk  which  is 
to  be  adapted  to  the  root  may  be  made  of  a  heavier  gauge  of  platinum 
when  indicated,  or  desirable,  in  the  manner  previously  recommended  in 
connection  with  the  "plate  and  dowel  croivn." 

This   procedure    is    also    equally   applicable    to 

Porcelain  Ulork.       porcelain  work,  and  when  porcelain  is  preferable  to 

the  use  of  gold  solder,  for  uniting  the  plate  to  the 

crown,  the  details  differ  only  in  dispensing  with  the  iirst  disk,  as  this 


Fiq.174, 


is  used  simply  as  a  backing  for  the  crown,  and  no  backing  becomes 
necessary  in  porcelain  work. 

The  adaptation  of  the  disk  to  the  base  of  the  root,  and  the  manner 
of  obtaining  and  sustaining  its  relation  to  both  the  crown  and  root,  may 
be  accomplished  as  indicated,  but  the  case  should  then  be  invested  and 
the  disk  permanently  attached  to  the  dowel  with  pure  gold,  or  twenty- 
five  per  cent  platinum  solder,  before  filling  the  intervening  space  with 
porcelain,  as  a  means  of  precluding  any  possible  change  of  relation 
which  may  accrue  as  a  result  of  the  shrinkage  of  the  porcelain  body  in 
fusing. 

Cbe  Brewster  Crown. 

Among  the  several  other  varieties  of  porcelain  crown  possessing 
fixed  dowels,  the  Brewster  crown,  designed  and  manufactured  by  Mu 
Robert  Brewster,  of  Chicago,  111.,  is  more  or  less  extensively  em- 
ployed 

It  is  made  of  porcelain  body,  quite  similar  to  Ash's  English  teeth. 
in  a  good  selection  of  moulds  and  colors,  with  a  slightly  concave  base, 


214 

and  a  round  dowel.  The  latter  is  made  of  a  composition  metal  similar 
to  the  alloy  of  German  silver,  and  is  attached  to  the  crown  with  a  low- 
fusing  body.  This  enables  it  to  possess  the  advantage  of  strength  and 
rigidity,  as  well  as  economy,  and  yet  the  attachment  between  crown  and 
dowel  seems  quite  secure  (Fig.  175,  A). 

The   application   of   this    crown   may  be   made 
Hppiication.  whenever  the  employment  of  a  fixed  dowel  crown 

is  indicated,  or  desirable ;  either  with  or  without  a 
band  or  plate;  and  the  detail  of  procedure,  in  each  instance,  is  identical' 
with  that  indicated  for  the  Logan  crown,  excepting  that  the  composi- 
tion of  the  dowel  and  its  manner  of  attachment  in  the  porcelain  pre- 
clude its  use  in  connection  with  porcelain  work,  where  it  is  necessarily 
subjected  to  a  high  degree  of  heat  in  the  furnace ;  though  the  same 
readily  admits  of  the  use  of  20  karat  solder. 

The  favorable  shape  of  both  crown  and  dowel,  and  the  comparative 
ease  with  which  it  may  be  procured  and  adjusted,  combined  with  its 


a 

inexpensiveness,  make  it  very  useful  for  temporary  purposes ;  but  when 
employed  as  a  permanent  crown  the  dowel  should  be  slightly  flattened 
on  at  least  one  side  (or  serrated),  in  order  to  facilitate  the  attachment 
of  the  cementing  medium,  and  thus  prevent  possible  rotation  or 
loosening. 

The  adaptation  of  the  base  of  the  crown  to  the  root  may  be  accom- 
plished with  greater  facility,  and  less  danger  of  grinding  the  dowel, 
by  the  use  of  curved  carborundum  wheels,  which  are  designed  and  rec- 
ommended by  Mr.  Brewster  for  this  purpose.     (Fig.  175,  B.) 

Cbe  **Tcllow$blp"  Crown. 

The  "Fellowship"  crown,  devised  and  manufactured  by  the  Dental 
Protective  Supply  Co.,  is  constructed  along  lines  similar  to  the  pre- 
ceding crown,  and  is  also  more  or  less  extensively  employed. 

Any  possible  rotation  of  the  crown  on  the  dowel,  or  in  its  attach- 
ment to  the  root,  is  prevented  by  the  shape  of  the  dowel,  and  the  manner 
in  which  it  is  attached  to  the  porcelain.  The  shape,  however,  is  similar 
to  that  of  the  dowel  of  the  Logan  crown,  and  in  consequence  possesses 


215 

the  same  objectionable  features,  it  is  made  of  a  German-silver  alloy, 
and  is  attached  in  the  crown  by  means  of  an  additional  piece  of  wire 
passing  laterally  through  perforations  in  the  base  of  the  crown  and  end 
of  the  dowel,  which  are  then  subsequently  filled  flush  with  low-fusing 
body.     (Fig.  176.) 

As  an  indication  of  the  recognition  of  the  ad- 

Scparable  vantages  of  a  separable  dowel,  all  of  the  ready-made 

Dowels.  crowns  originally  made  with  fixed  dowels — except  tlie 

last  mentioned — are  now  made  with  separable  dowels. 

In  the  event  of  the  subsequent  occurrence  of  a  fracture  of  the  porce- 
lain in  any  of  the  various  forms  of  fixed-dowel  crowns,  the  method  of 
repair  is  often  difficult  and  sometimes  even  impossible ;  and  the  best 


BjJ76, 

results  are  usually  accomplished  by  removing  the  remaining  dowel  and 
adapting  a  new  crown. 

When  it  has  been  mounted  with  cement,  however,  and  particularly 
in  small  constricted  roots,  this  is  often  a  difficult  and  sometimes  dan- 
gerous procedure ;  but  may  be  accomplished  by  drilling  out  the  cement 
immediately  surrounding  the  dowel  with  a  very  small  round  bur  until  it 
may  be  gradually  loosened  and  removed,  in  which  extreme  care  must 
be  exercised  to  prevent  perforating  the  root  or  breaking  oft  the  dowel  at 
a  point  which  will  likely  preclude  the  removal  of  its  apical  end. 

In  very  small  roots  or  where  either  of  the  latter  results  seem  at  all 
probable,  the  method  suggested  by  Dr.  Joseph  Head,  of  Philadelphia, 
may  be  employed  to  advantage.  This  consists  in  cutting  the  dowel  into 
two  lateral  halves  by  drilling  vertically  through  its  smallest  diameter 
with  a  small  round  bur,  and  when  so  divided,  the  space  thus  produced 
will  admit  of  loosening  each  half  until  their  separate  removal  may  be 
effected  without  danger  of  weakening  the  root.  A  ])air  of  forceps 
designed  especially  for  this  purpose  by  H.  X.  Lancaster  may  also  be 
found  very  useful. 


2l6 

In  those  cases  where  the  dowel  remains  firm  in  its  attachment  to 
the  root,  and  the  lengtli  and  strength  of  its  projecting  end  will  afford 
adequate  means  of  sustaining  a  new  porcelain  crown,  it  may  often  be  left 
in  place  and  a  Davis  crown  adapted  to  the  root  and  then  cemented  to  it; 
or,  a  crown  may  be  constructed  possessing  a  socket  in  its  base  which  will 
fit  and  engage  the  projecting  end  of  the  dowel  and  securely  sustain  it 
in  its  proper  relation,  when  mounted  with  cement.  As  this  latter  pro- 
cedure involves  the  construction  of  a  crown  which  may  often  be  found 
useful  and  practical  it  will  be  separately  considered  under  the  classifi- 
cation of  tube  crowns. 

Vklt  Crowns. 

This  style  of  crown  is  adaptable  to  that  class  of  cases  previously 
referred  to  wherein  the  original  has  been  broken  away  leaving  the  dowel 
still  firm  in  its  attachment  to  the  root ;  and  may  be  employed  as  a  means 
of  substituting  a  well  adapted  crown  when,  for  any  reason,  it  may  not 
be  deemed  advisable,  or  desirable,  to  remove  the  remaining  dowel. 

The  application  of  such  a  procedure  and  of  the  principles  involved 
was  probably  first  suggested  by  Dr.  Wm.  Mitchell,  of  London,  England, 
but  is  also  advocated  and  employed,  as  applied  particularly  to  porcelain 
work,  by  Dr.  Jas.  E.  Keefe,  of  Chicago,  111.,  and  Dr.  F.  J.  Capon,  of 
Toronto,  Canada. 

While  the  application  of  such  crowns  is  neces- 

Hpplication.  sarily  confined  to  repair  work,  they  are  equally  ap- 

plicable to  cases  where  the  original  crown  pos- 
sessed a  band  and  cap,  which  may  or  may  not  remain  securely  in  place, 
as  well  as  to  those  where  no  band  was  used,  so  long  as  the  dowel  itself 
remains ;  but  the  strength  in  the  attachment  of  the  new  crown  will  of 
course  depend  upon  the  length  of  the  end  of  the  dowel  exposed  and 
projecting  beyond  the  surface  of  the  cap,  or  root,  which  may  be  tele- 
scoped by  the  tube. 

When  this  is  inadequate  the  opportunities  for  securing  sufficient 
integrity  may  be  increased  by  drilling  out  the  cement  around  the  dowel, 
and  thus  trephining  its  end,  with  a  small  round  bur,  until  a  greater 
length  is  exposed ;  but  where  a  cap  remains,  unless  the  dowel  projects 
sufficiently  far  beyond  it,  such  access  and  possibilities  may  indicate  its 
destruction  and  removal. 

When  the  dowel  has  been  thus  exposed  so  as  to  insure  sufficient 
stability  in  the  attachment  of  the  crown,  its  end  should  be  squared  up 
and  properly  shaped  to  admit  of,  and  facilitate,  the  adaptation  and 
easy  removal  of  a  telescoping  tube.      (hig.    177,  A.) 


This  tube  should  be  made  of  pure  gold  or  plati- 

^COCCdure.  num,  about  36  gauge,  and  may  be  formed  on  a  piece 

of  wire  previously  selected  for  the  purpose,  and  a 

trifle  larger  in  diameter  than  the  dowel ;  or  joil  may  be  used  and  adapted 

directly  to   the    dowel,   if  subsequently   reinforced   with   solder ;  which 

should  be  also  observed  even  in  the  former. 

When  made  and  fitted,  the  joint  should  be  soldered,  and  the  tube 
then  adjusted  to  the  dowel.  A  disk  of  pure  gold  or  platinum,  as  the  re- 
quirements of  the  intended  construction  may  indicate,  about  36  gauge, 
should  now  be  perforated  to  fit  closely  over  the  tube,  burnished  to  a 
close  adaptation  to  the  root,  and  trimmed  to  follow  its  peripheral  outline. 
The  surplus  end  of  the  tube  should  now  be  cut  off  even  with  the  end  of 
the  dowel,  and  the  proper  relation  between  it  and  the  disk  securely  sus- 
tained with  adhesive  wax,  when  they  may  be  detached  from  the  root  and 
invested  and  soldered,  at  which  time  the  open  end  of  the  tube  presenting 


fJcj.177. 

toward  the  incisal  edge  should  be  closed.  This  affords  an  accurately 
adapted  base  for  the  subsequent  construction  of  a  crown  in  the  ordinary 
manner,  using  a  facing  in  combination  with  either  gold  or  porcelain, 
which  may  then  be  finished  and  mounted  with  cement. 

The  completed  crown  for  that  class  of  cases  where  the  end  of  the 
dowel  projects  far  enough  beyond  the  base  of  the  root  to  afiford  adequate 
stability  in  the  attachvnent  is  illustrated  in  Fig.  177,  B  ;  while  the  con- 
struction for  those  cases  wherein  the  end  of  the  dowel  is  trephined  and 
the  tube  thus  extended  into  the  root,  as  a  means  of  securing  greater 
integrity,  is  illustrated  in  Fig.  177,  C,  and  the  relation  of  the  finished 
crown  to  the  root  and  dowel  in  the  former  class  is  illustrated  in  Fig. 

C.«.porarv  Cr.«»«. 

The  employment  of  temporary  crowns  become  necessary  in  emer- 
gency cases  where  immediate  substitution  of  the  lost  natural,  or  broken 
artificial,  crown  is  required;  and  is  indicated  in  the  construction  of  per- 


2l8 

manent  crowns  for  the  anterior  teeth,  for  the  purpose  of  relieving  the 
patient  of  temporary  disfigurement  and  embarassment  during  the  pro- 
cedure. Their  use  also  materially  facilitates  the  subsequent  adjustment 
and  rnounting  of  the  permanent  crown  by  keeping  the  gum  packed 
away  and  preserving  a  free  exposure  of  the  end  of  the  root,  during  tne 
interim. 


Fit].  1 78. 

In  view  of  the  possible  advantages  thus  derived 
Indications.  from  their  use  in  the  application  of  dowel  crowns, 

and  particularly  in  the  mouths  of  women,  they 
should  be  invariably  employed  whenever  the  time  required  to  complete 
the  construction  of  a  permanent  crown  preclufdes  finishing  and  mount- 
ing the  latter  on  the  same  day  on  which  the  root  is  prepared. 

While  almost  any  of  the  fixed-dowel  crowns,  and  especially  the  less 
expensive  ones,  will  often  answer  this  purpose,  and  even  the  old-style 
English  tube-teeth  may  be  employed,  the  most  simple,  expeditious  and 
inexpensive  method  consists  in  using  an  ordinary  long-pin  facing,  and 
constructing  the  crown  for  the  individual  case. 


F/CJJ79. 

To   facilitate   the   application,   at  least   a  small 
Procedure.  selection  of  facings  for  the  six  anterior  teeth  should 

be  kept  on  hand.  One  suitable  to  the  requirements 
of  the  case  in  size,  shape  and  color,  should  then  be  selected  and  ground 
to  a  fairly  good  adaptation,  and  a  dowel  then  made  of  German-silver 
wire.  Such  wire  is  convenient  for  many  purposes  and  may  be  easily 
procured  in  six-inch  lengths  of  various  sizes  from  jewelers'  supply 
houses.     Fig.  178. 


219 

A  proper  length  and  size  of  dowel  should  be  cut,  one  end  slightly 
tapered  with  a  file,  and  the  other  flattened  with  a  small  hammer  on  the 
anvil,  Fig.  179,  or  by  pressing  between  rollers,  Fig.  180,  both  of  which 
are  useful  appurtenances  for  the  well  equipped  laboratory,  until  it 
is  broad  enough  to  fit  in  snugly  between  the  pins.  This  is  done  for  the 
purpose  of  facilitating  the  attachment  of  the  facing,  and  preventing  any 
obstruction  to  the  occlusion,  but  should  not  be  done  with  a  file,  because 
of  thus  unnecessarily  diminishing  the  strength  of  the  dowel  at  this 
point. 

The  most  convenient  method  of  attaching  the  facing  and  dowel  has 
been  suggested  by  Dr.  W.  H.  Taggart,  of  Chicago,  111.     In  this  pro- 


Ficj.180, 

cedure  the  flattened  end  of  the  dowel  is  made  somewhat  broader  than 
the  space  between  the  pins  of  the  facing,  and  then  notched  with  the 
edge  of  a  file  until  it  may  be  slipped  into  place,  with  the  pins  fitting 
closely  into  the  notches.  The  permanent  relation  between  the  two  may 
then  be  securely  sustained  by  bending  the  pins  over  upon  the  dowel. 

The  dowel  should  now  be  bent,  if  necessary,  until  the  crown  may 
be  properly  adjusted  to  position  on  the  root,  when  it  should  be  mounted 
with  temporary  stopping  or  gutta  percha,  with  which  the  desired  con- 
touring of  the  lingual  surface  can  also  be  made.  The  consecutive  steps 
of  this  entire  procedure  are  illustrated  in  Fig.  181. 


220 

Temporary  stopping  may  be  used  with  greater  facility  and  pos- 
sesses sufficient  integrity  to  serve  the  purpose  for  a  few  days,  but  when 
the  crown  is  to  be  worn  for  a  longer,  or  more  indefinite  period,  gutta 
percha  should  be  used. 

Although  the  detail  incident  to  the  construction  of  such  crowns 
consumes  but  five  or  ten  minutes'  time,  an  assortment  of  these  dowels 
may  be  made  at  convenient  opportunities,  and  kept  for  subsequent  use, 
which  will  further  expedite  the  work. 

The  relation  between  facing  and  dowel  may  be  also  sustained  by  the 
use  of  either  hard  or  soft  solder,  if  desirable,  but  a  more  secure  attach- 
ment than  is  afiforded  by  the  above  method  is  seldom,  if  ever,  required. 

In  the  use  of  gold  or  silver  solder  for  such  purposes  the  facing  and 
dowel  should  be  attached  by  bending  the  pins,  and  the  whole  then  in- 
vested and  soldered  in  the  usual  manner.  In  using  soft  solder,  however, 
no  investment  is  necessary  if  the  facing  and  dowel  are  placed  upon  a 
slightly  heated  charcoal  or  asbestos  block  or  in  a  bed  of  asbestos  fibre; 


^'9 


J8L 


the  proper  flux  then  applied,  and  evaporated  with  heat,  and  the  solder  then 
fused  by  slowly  directing  the  flame  of  a  Bunsen  burner  or  alcohol  lamp 
upon  the  facing. 

A  more  artistic  and  finished  contour  of  the 
U$C  Of  nmalgam.  lingual  surface,  as  well  as  a  more  permanent  adapta- 
tion of  such  crowns  may  be  obtained  by  placing  the 
facing  and  dowel  (after  their  attachment)  upon  the  root,  and  packing 
plastic  amalgam  over  its  end,  and  around  the  dowel,  to  the  desired  contour. 
After  this  has  crystallized,  it  may  be  finished  and  polished,  and  then 
mounted.  This  procedure  consumes  more  time,  and  entails  more  work 
than  is  usually  indicated  or  warrantable  for  temporary  purposes. 

More  artistic  and  permanent  results  may  also 
Use  Of  UulcanitC.  be  obtained  by  adapting  the  base  and  forming  the 
lingual  contour  with  wax,  and  subsequently  flask- 
ing  the  crown  and  replacing  the  wax  with  vulcanite.  In  the  process, 
however,  it  becomes  necessary  to  "tin"  the  German-silver  dowel,  so  that 
the  vulcanite  may  become  attached  to  it,  and  the  entire  procedure  re- 
quires more  time  than  that  incident  to  the  construction  of  a  crown  in  a 
more  practical  and  artistic  manner. 


Jfppllcdticn  and  Construction  of  Porcelain  c;ro\vn$o 


CHAPTER  XII. 


Contraindications.     Indications.      Advantages:    Esthetic;     Anterior    Crowns,     Bi- 
cuspid Crowns,  Molar  Crowns.      Hygienic.     Mechanical;  Attachment  of  Facing, 
Attachment  of  Molar  and   Bicuspid  Crowns  to   Root.     Application:    Require- 
ments; Strength  of  Metal  Construction,  Soldering,  Oxyhydrogen  Flame,  Root 
Preparation.     With  Band  and  Dowel;  Bands,  Floor,  Dowels,  Accurate  Fit- 
ting Dowels,  Impression  and  "Bite,"  Facing,  Investment,  Soldering  Facing, 
Anterior  Crowns,  Bicuspid  Crowns,  Molar  Crowns  ;  With  Facing,  With- 
out Facing.  Variations  in  Construction :  Re-enforced  Caps  ;  Grinding 
off  Pins.    Leaving  Pins  Exposed.    Without  Band;  Procedure,  Plate 
and  Dowel.     Partial  Bands;  Procedure.     Jacket  Crowns ;  Indica- 
tions for   Porcelain  Jackets,  Procedure.     Variation  of  Method. 
The  Spaulding  All-Porcelain   Crown.     Use  of  the  Davis  and 
Logan  Crowns;  Advantages,   Disadvantages.     Application 
of  the  Davis  Crown,  With  Band,  Without  Band.     Appli- 
cation     of     the     Logan     Crown  ;      Procedure.        Use 
of    "Plastic"    or     "  Mouldable''      Porcelain. 
Johnston's    Method. 


After  having  passed  through  the  various  experimental  stages  in- 
cident to  the  development  of  its  possibilities,  the  application  of  porcelain 
work,  or  the  ceramic  art  has  opened  one  of  the  most  artistic  and  prac- 
tical fields  of  dentistry,  and  is  without  doubt  destined  to  become  a  perma- 
nent part  of  modern  practice. 

While  the  primitive  efforts  in  this  line  were  fraught  with  many  dis- 
couraging phases,  and  replete  with  failures,  and  much  of  the  resultant 
development  must  be  attributed  to  the  ever-increasing  and  constantly  im- 
proving facilities ;  yet,  throughout  the  entire  era  of  its  employment,  from 
the  time  when  the  material  was  supplied  in  only  one  or  two  grades  and 
colors ;  when  the  coke  furnaces  afforded  the  only  adequate  means  for 
obtaining  sufficient  heat,  and  when  the  "baking"  of  a  case  required  con- 
siderable effort  and  consumed  much  time,  until  the  present,  when  it  can 


222 

be  procured  in  several  grades  and  in  varying  colors ;  when  the  same 
procedure  may  be  accomplished  in  the  operating  room  in  the  presence  of 
the  patient,  instead  of  the  laboratory,  at  night ;  and  at  the  expense  of  but 
little  time  or  effort,  the  possibilities  of  such  work  from  an  artistic  point 
of  view  have  always  been  fully  appreciated. 

Since  porcelain  is  a  mineral  substance,  however,  and  in  consequence 
possesses  the  characteristic  of  friability,  the  possibilities  from  the  view- 
point of  strength — which  as  a  requirement  is  of  equal  importance  with 
the  esthetic — have  been  observed  and  recognized  only  in  its  more  modern 
application ;  and  have  been  attained  mainly  as  the  result  of  continued 
experimentation  on  the  part  of  those  who  were  sufficiently  enthusiastic 
and  progressive  to  ascertain  the  causes  of  failures,  and  endeavor  to  over- 
come them  by  the  elimination   of  weak  points. 

As  a  result,  the  use  of  porcelain  in  its  present  form,  and  with  the 
facilities  available,  make  it  possible  for  the  skilful  and  experienced  ope- 
rator to  achieve  results  which  combine  both  of  these  requirements  to  a 
high  degree.  This  is  especially  true  of  its  application  to  crown  and 
bridgework,  in  which  its  conservative  employment  may  be  productive  of 
a  class  of  work  which  more  closely  approaches  the  ideal  than  any  other, 
by  conserving  the  very  highest  possible  esthetic  and  mechanical  require- 
ments. 

In  view  of  the  friable  nature  of  porcelain,  however,  the  desired  and 
necessary  degree  of  strength  is  not  to  be  obtained  from  thin  layers,  or 
veneers,  but  is  dependent  upon  the  presence  of  a  sufficient  thickness  to 
insure  the  requisite  resistance  to  stress.  For  this  reason  the  possible 
strength  of  such  work  will  naturally  increase  in  proportion  to  the  quantity 
which  may  be  used  in  the  individual  case,  or  in  proportion  zvith  the  bulk; 
and  for  the  latter  reason,  porcelain  work  in  any  of  its  phases  is  not  uni- 
versally applicable,  but,  on  the  contrary,  has  its  definite  prescribed  limita- 
tions. 

Hence  the  entire  practicability  of  this  class  of  work  will  depend  upon, 
first,  conservative  or  judicious  application,  and  second,  a  skilful  execution 
of  all  of  the  details  incident  to  the  construction. 

The  absolute  necessity  for  scrupulous  attention  to  detail,  and  for  the 
utmost  of  painstaking  care  in  its  execution  accounts  to  a  large  extent  for 
the  occurrence  of  failures,  and  elevates  this  class  of  work  to  a  plane  some- 
what beyond  the  ordinary.  Indeed,  the  successful  manipulation  of  porce- 
lain promotes  and  demands  the  acquirement  of  a  degree  of  skill,  and  the 
cultivation  of  an  artistic  temperament,  which  is  far  beyond  the  province 
of  those  whose  efforts  are  more  or  less  encompassed  within  the  range  of 
indifference. 

While  failures  will  occur  in  any  line  of  work,  a  very  large  proportion 


223 

of  them  in  this  particular  class  can  invariably  be  attributed  to  an  inade- 
quate conception  of  the  requirements,  or  injudicious  application;  or  to 
unskilful  or  faulty  construction  and  manipulation ;  either,  or  all,  of  which 
should  reflect  upon  the  inexperience  or  indifference  of  the  operator  rather 
than  to  cause  or  result  in  a  premature  condemnation  of  principles,  methods 
and  materials  involved. 

Contraindications. 

For  these  apparent  reasons  the  application  of  porcelain  to  the  con- 
struction of  individual  croivns,  to  which  consideration  this  chapter  will 
be  exclusively  devoted,  is  contraindicated  in  all  cases  where  the  maximum 
length  of  the  crown,  or  the  close  occlusion  of  the  opposing  teeth,  precludes 
the  presence  of  porcelain  in  sufficient  thickness,  or  bulk,  to  insure  an  ade- 
quate degree  of  strength;  and  where  nothing  but  an  indestructible  sub- 
stance, like  metal,  could  be  relied  upon  to  withstand  the  stress  of  masti- 
cation. 

Indications. 

As  such  cases  present  the  exceptional,  rather  than  the  usual  condi- 
tions, however,  and  hence  constitute  a  small  percentage  of  those  requiring 
a  restoration  of  the  natural  crown,  the  application  of  porcelain  crowns, 
properly  constructed,  is  especially  indicated  on  the  ten  anterior  teeth,  and 
not  infrequently  upon  the  molars,  in  all  cases  which  present  a  normal  or 
average  favorable  occlusion. 

Jldvantagcs. 

The  special  advantages  to  be  obtained  from  the  application  of  porce- 
lain crowns  lie  in  the  artistic  manner  and  facility  with  which  the  natural 
conditions  and  varying  characteristics  may  be  closely  simulated ;  the  hygi- 
enic qualities  of  the  material,  and  the  possibilities  for  comparative  and 
relative  strength.  These  may  be  classified  as  esthetic,  hygienic  and  me- 
chanical and  each  will  be  separately  considered. 

\\'hile    the    possibilities    for    avoiding  anv  dis- 
€$tbctlc.  play    of    gold    arc    always    very    advantageous    this 

esthetic  feature  is  further  supplemented  by  the  ab- 
sence of  a  metal  backing,  the  use  of  which  particularly  on  the  anterior 
teeth  is  always  more  or  less  objectionable. 

In   the   construction   of  crowns   for  the  six  an- 

Jlnterior  Crowns,      terior  teeth   the  reflection  of  the   rays  of  light  and 

its  variations  bear  materially  upon  the  color  problem, 

and  more  artistic  results  are  always  to  be  obtained  from  the  absence  of 

a  metal  backing  for  the  reason  that  its  presence  destroys  the  translucency 

of  the  porcelain  facim^;  changes  its  color,  and  often  occasions  the  appear- 


224. 

ance  of  a  dark  blue  line  along  the  point  between  facing  and  backing.  This 
latter  unsightly  and  unhygienic  condition  is  due  to  the  penetration  and 
decomposition  of  secretions,  and  is  of  course  decidedly  objectionable. 
While  the  translucency  of  the  facing  is  slightly  diminished  even  in  a 
porcelain  crown,  it  is  by  no  means  destroyed,  and  the  other  objectionable 
features  are  entirely  eliminated,  all  of  which  are,  particularly  in  thi^ 
region,  especially  important  considerations. 

In  the  restoration  of  the  crowns  of  bicuspids 
Bicuspid  €r9Wn$.  the  employment  of  porcelain  is  especially  indicated 
because  of  the  difficulty  of  obtaining  the  same 
esthetic  effect,  combined  with  the  required  degree  of  strength,  in  any 
other  style  of  construction.  Indeed  the  ease  and  facility  with  which 
both  of  these  features  may  be  obtained,  as  compared  with  any  other  style 
of  crown,  causes  its  application  to  be  pre-eminently  indicated  on  these 
teeth. 

Although  color  and  translucency  are  not  so 
molar  Crowns.  essentially  important  a  consideration  in  crowning  the 
molars,  and  granting  the  previously  mentioned  ad- 
vantages of  the  gold  shell  or  telescope  crown  for  these  teeth,  there  are 
nevertheless  frequent  indications  for  the  application  of  porcelain  crowns. 
Often  on  the  first,  and  occasionally  on  the  second  molars,  and  particularly 
in  the  mouths  of  women,  gold  crowns  are  more  or  less  conspicuous,  anc 
the  use  of  porcelain  may  serve  a  highly  esthetic  purpose  in  these  cases 

The  hygienic  properties    of    a    smooth,  highly 
l)ygicnic.  vitrified  surface,  like  that  which  presents  in  porce- 

lain, constitute  an  important  advantage  of  inestim- 
able value  in  the  mouth.  Such  a  surface  is  more  easily  kept  clean  than 
that  of  gold  because  it  is  immune  to  the  chemical  action  of  the  secretions, 
and  food  products  will  not  cling  to,  become  deposited  upon,  or  be  ab- 
sorbed by"  it.  For  this  reason,  and  possibly  also  because  of  its  property  of 
slow  conductivity,  it  is  least  irritating  to,  and  most  compatible  with,  the 
tissues  of  the  mouth. 

Those  advantages   which    have    been    classified 
mechaniCHl.  as  mechanical  will  be  considered  from  the  view-point 

of  the  relative  degree  of  possible  strength  which 
may  be  obtained  both  in  the  construction  of  the  crown,  and  in  its  attach- 
ment to  the  root. 

As  the  attachment  of  the  facing  is  usually  the 

HttacbmCNt  of  Tacing.   weakest  point  in  the  construction  of  dowel  crowns, 

in  this  connection  the  relative  strength  to  be  obtained 

from  this  style  of  construction  as  compared  with  a  metal  backed  crown 

is  a  matter  of  much  concern  and  of  appreciable  importance. 


225 

The  probability  of  the  subsequent  occurrence  of  fractured  facings 
in  [porcelain  crown  work  is  reduced  to  a  minimum  for  the  reason  that, 
in  a  metal  backed  crown  the  facing  is  attached  to  the  l^acking  simply  and 
only  by  means  of  the  attachment  pins,  while,  in  a  porcelain  crown,  this 
same  attachment  is  also  secured  and  then  further  supplemented  by  the 
fusion  of  the  porcelain  over  the  entire  lingual  surface  of  the  facing. 

The  additional  strength  thus  obtained  by  this  combined  means  of  at- 
tachment makes  it  practically  impossible  for  the  facing  to  be  broken  away 
from  a  well  constructed  crown.  When  such  breakage  or  accident  does 
occur,  the  entire  mass  of  porcelain,  including  facing,  will  usually  separate 
from  the  cap,  which  rarely  happens,  and  which  can  be  quite  as  often 
attributed  to,  and  invariably  indicates,  faulty  construction  of  the  crown 
with  regard  to  the  means  observed  for  the  support  and  retention  of  the 
porcelain. 

In  the  attachment  of  molar  and  bicuspid  crowns 
JIttacbmcnt  of  lHoIar  to  the  root  a  possible  mechanical  advantage  is  also 
and  Bicuspid  6fOWH$.  possessed,  even  over  gold  crowns,  because  of  the 
greater  facility  with  which  a  sJiort  projecting  end 
of  the  root  may  be  properly  prepared,  and  a  narrozu  band  accurately  fitted, 
as  compared  with  the  requirements  incident  to  shaping  a  longer  project- 
ing end  of  the  root  and  adapting  a  wider  band. 

While  the  latter  procedure  may  be  somewhat  more  difficult,  any  pos- 
sible advantage  reverts,  however,  to  the  degree  of  skill  with  which  the 
detail  is  executed,  and  unless  the  esthetic  requirements  indicate  the  appli- 
cation of  a  porcelain  crown,  or  the  root  is  primarily  destroyed  to  a  close 
proximity  with  the  gum  line,  the  preference  should  usually  be  given  to 
the  gold  crown  because  of  the  conservation  of  tooth  structure,  and  of  the 
increased  strength  in  the  attachment  between  crown  and  root  which  may 
possibly  be  obtained  in  the  use  of  a  wider  telescoping  band. 

JlpplicatiOH. 

In  the  application  of  this  class  of  crown  construction  the  highest  pos- 
sible advantages  can  be  derived  only  from  a  careful  observation  of  the 
requirements,  combined  with  a  skilful  execution  of  the  details  in  the 
preparation  of  the  root;  the  construction  and  adaptation  of  the  cap,  and 
attachment  of  the  facing  ;  and  the  manipulation  of  the  "body"  itself. 

When  the  conditions  of  occlusion  arc,  or  may  be  made,  favorable, 
and  when  these  details  of  construction  have  been  executed  with  skill,  a 
porcelain  crown  possesses  adequate  strength  to  meet  the  requirements 
in  all  average  and  typical  cases ;  and  the  possible  integrity  in  such  work 
often  exceeds  that  of  anv  other  stvle  of  construction. 


226 

To  obtain  such  results  with  a  maximum  degree 
Rt(|Uircin(nt$.  of  strength,  however,  three  essential  requirements 
must  be  observed :  First,  the  cap,  or  base,  of  the 
crown  must  be  inherently  strong  enough  to  retain  its  shape,  and  afiford 
ample  means  of  attachment  and  support  to  the  porcelain.  Second,  the 
facing  must  be  properly  adapted,  and  securely  attached  to  the  cap ;  and 
third,  the  selection  and  manipulation  of  the  "body"  must  be  made  with  a 
view  to  securing  the  best  possible  results. 

In  order  that  the  requisite  strength  may  exist 

Strcngtl)  Of  metal      in  the  metal  parts  they  must  be  made  of  a  material 

Construction.  which  will  withstand  the  degree  of  heat  required  to 

fuse  the  porcelain ;  and  a  gauge  sufficiently  thick  to 

retain  its  given  shape  must  be  used.     Because  of  the  practical  infusibility 

of  platinum,  of  its  malleability,  slight  susceptibility  to  oxidation,  and  to 

the  chemical  action  of  the  secretions,  it  is  used  almost  exclusively  for  all 

of  the  parts  for  this  work,  excepting  the  dowel.     For  this  purpose  the 

alloy  of  platinum  and  iridium  is  used  because  of  the  softness  of  platinum 

alone,  and  of  the  additional  stiffness  imparted  by  the  incorporation  of 

various  proportions  of  the  latter  metal. 

In   soldering  the   various  parts   perfect  contact 
Soldcrins.  between  all  joints  to  be  united  should  exist,  and  their 

union  must  be  effected  with  a  grade  of  solder  which 
will  not  be  disturbed  or  re-fused  in  the  subsequent  "baking"  of  the  crown. 
For  this  reason  25;^  platinum  solder  should  be  used  throughout  the  entire 
assemblage  of  metal  parts  if  the  greatest  degree  of  strength  is  to  be  ob- 
tained, and  its  use  is  absolutely  necessary  wherever  contact  does  not  exist. 
In  the  construction  of  single  crowns,  however,  all  of  the  soldering 
may  be  done  successfully  with  the  use  of  pnre  gold  as  a  solder,  provided 
that  absolute  contact  of  the  parts  has  been  secured,  and  that  the  gold  is 
then  thoroughly  fused  until  all  surplus  disappears  by  becoming  absorbed 
by,  and  alloyed  with,  the  platinum. 

This  may  be  easily  accomplished  by  the  continued  application  of  a 
small  pointed  flame  from  the  ordinary  combination  mouth  blow-pipe,  and 
will  be  indicated  by  the  disappearance  of  the  surplus,  and  the  blending 
of  its  color  into  that  of  the  platinum.  To  secure  this  result  with  facility, 
however,  it  is  highly  important  that  only  enough  gold  should  be  used  to 
make  the  joint,  and  such  a  union  will  possess  strength,  and  successfully 
withstand  the  degree  of  heat  necessary  to  fuse  the  porcelain. 

•  Should  absolute  contact  not  exist  at  any  point  in  the  joint  the  disap- 
pearance of  the  pure  gold  scjklcr,  which  may  be  due  cither  to  absorption 
or  to  volatilization,  will  result  in  a  subsequent  oj^cning  and  weakening  of 
the  joint,  citlicr  from  the  heat  of  the  blow-pipe  or  furnace. 


22y 

In  the  use  of  platinum  solders,  whether  or  not 

Oxybydroflen  Tlame.    an  investment  is  employed,    the    use    of    the    oxy- 

hydrogen  flame  is  expedient,  and  often  absolute!}- 

essential,  and  while  the   same  might  also  be  used  with  pure  gold,  it  is 

entirely  unnecessary. 

As.^those  requirements  incident  to  the  attachment  of  the  facing,  and 
the  manipulation  of  the  body,  constitute  important  procedures  in  the  con- 
struction of  the  crown,  they  will  be  considered  in  regular  order. 

The  requirements  of  root  preparation  are  sim- 

Koot  Preparation.       ilar  to  those  previously  indicated  in  the  application 

of  any  of  the  various  styles  of  dowel  crowns,  with 

the  exception  that,  for  porcelain  work,  the  root  should  be  cut  down  until 

as  short  as  consistent  in  order  to  secure  as  much  space,  and  make  as  much 

accommodation  for  the  porcelain  as  possible. 

While  an  unnecessary  waste  or  sacrifice  of  tooth  structure  is  to  be 
condemned  as  a  general  practice,  for  the  above  reason  the  root  should 
be  cut  shorter  for  porcelain  crowns  than  for  any  other  style  of  construc- 
tion, but,  if  a  band  is  to  he  employed  a  projecting  surplus  end  should  al- 
ways be  allowed  to  remain  until  the  peripheral  trimming  has  been  accom- 
plished, the  measurement  taken,  and  the  hand  fitted.  This  is  necessary 
for  the  reasons  previously  mentioned  in  connection  with  the  "band  and 
dowel"  crown,  and  the  same  shape  is  indicated  for  the  basal  end  of  the 
root  as  formerly  recommended  and  illustrated  for  anterior  roots  in  Fig. 
50,  and  for  bicuspid  and  molar  roots  in  Fig.  53. 

Ulitb  Band  ana  Dowel. 

As  the  employment  of  a  band  is  generally  conceded  to  be  productive 
of  the  most  universally  successful  results,  this  style  of  construction  will 
be  given  precedence  in  this  consideration,  and  be  followed  by  the  varia- 
tions, the  indications  for  the  application  of  each  of  which  having  been 
previously  mentioned. 

The    band    should    be    made    of    platinum    not 
Bands.  thicker  than  28  nor  thinner  than  29  gauge,  and  the 

edges  should  be  slightly  overlapped  before  solder- 
ing. This  method  should  be  observed  as  a  means  of  securing  additional 
strength,  and  of  precluding  the  subsequent  opening  of  the  joint  from 
the  expansion  of  the  metal  which  is  induced  by  the  degree  of  heat  neces- 
sary to  fuse  the  porcelain.  The  exact  length  of  the  measurement  of  the 
root,  taken  in  the  ordinary  manner,  and  cut  and  straightened  as  indi- 
cated, should  be  designated  by  cutting  a  small  nick  in  the  edge  of  a  piece 
of  platinum  plate  from  which  the  band  should  then  be  cut  about  ^/^  of  an 
inch  wide,  and  with  an  allowance  of  about  i/i6of  an  inch  surplus.    (Fig. 


228 


182A.)  Each  end  should  then  be  sHghtly  beveled  on  one  side  with  a 
file,  and  the  band  then  annealed  and  made  in  circular  form,  with  the  sur- 
plus end,  designated  by  the  nick,  overlapping  the  outside  of  the  other 
end  until  the  nick  approximates  evenly  with  this  edge.     (Fig.  182  B.) 

The  surplus  overlapping  end  must  be  on  the  outside  to  prevent 
diminishing  the  size  of  the  band,  and  the  relation  may  then  be  sustained 
bv  pinching  the  ends  closely  together  with  flat-nose  pliers,  which  pro- 
duces a  sharp  angle  on  each  side  of  the  joint  and  affords  a  flat  surface 
contact.  (Fig.  182  C.)  This  will  usually  overcome  a  change  in  the  re- 
lation as  the  result  of  expansion  when  heated,  though  a  wire  may  be 
twisted  around  the  band  for  this  purpose  if  necessary. 

The  joint  should  then  be  soldered  with  a  jnininitun  quantity  of  25 
per  cent  platinum  solder,  or  with  pure  gold,  to  prevent  unnecessary  stiff- 
ness, in  the  manner  indicated. 


nq.182.. 

The  band  should  now  be  trimmed  to  follow  the  cervical  curvature 
of  the  gum,  the  edge  nicely  rounded,  and  then  fitted  to  the  root,  and 
afterward  cut  away  until  as  narrozv  as  possible,  in  accordance  with  the 
detail  previously  described. 

The  floor  should  be  of  about  32  gauge  platinum 
floor.  cut  somewhat  larger  than  the  diameter  of  the  band. 

The  band  should  be  placed  in  position  on  it,  and 
first  simply  tacked  to  place  with  a  small  quantity  of  solder.  This  primary 
attachment  secures  the  relation  and  anneals  the  floor  metal  so  that  it  may 
then  be  easily  Imrni.shed  into  close  and  direct  contact  with  the  edge  of 
the  band,  without  danger  of  changing  the  shape  of  the  latter. 

The  soldering  may  now  be  completed  in  which,  if  pure  gold  is  used, 
it  must  be  carefully  noted  that  perfect  contact  exists  around  the  entire 
joint,  alter  which  the  sur])lus  may  be  trimmed  away  and  finished  down 
with  file  and  disks  until  flush  with  the  edge  of  the  band. 


229 

The  dowel  should    be    made    of    round    iridio- 
DOWClS.  platinum   zvirc  of  a  size  proportionate  with  the  size 

of  the  root  and  requirements  of  the  crown,  and  fitted 
to  the  canal  in  the  manner  previously  outlined. 

The  cap  should  now  be  adjusted  to  place  on  the  root,  the  floor 
slightly  perforated  for  the  dowel  at  the  proper  point,  and  this  perfora- 
tion then  enlarged  zvitJi  the  dozvcl  by  forcing  it  to  place.  This  insures 
a  perfect  contact  between  them  which  is  essential  to  the  strength  of  their 
union,  and  to  the  facility  with  which  it  may  be  accomplished. 

The  relation  should  now  be  temporarily  sustained  with  gutta-percha 
or  adhesive  wax,  until  they  may  be  removed,  invested,  and  soldered  as 
indicated.  While  any  means  of  investment  is  often  unnecessary  because 
of  the  close  relation  thus  existing,  the  simple  means  previously  advo- 
cated for  this  insures  their  proper  relation. 

Where  it  may   be  desirable  to  have  the  dowel 

JlCCUrate  Titling       fit  closely  to  the  walls  of  the  canal  throughout  its 

Dowels.  entire   length,   the  method   suggested  by  Dr.  A.  O. 

Hunt,  and  others  may  be  used  to  advantage.     This 

consists   in   rolling  platinum  foil    i-iooo  into  a  cone,  passing  this  cone 

into  the  canal  and  expanding  it  first  with  a  tapering  pointed  instrument, 

and  then  by  packing  cotton  into  it,  until  it  conforms  to  the  shape  of  the 

canal.     It  may  now  be  removed  and  filled  with  platinum  solder,  and  then 

adjusted  to  its  proper  relation  with  the  cap,  as  indicated. 

The  same  procedure  is  also  applicable  to  any  kind  of  crown  con- 
struction, and  for  gold  work  the  cone  may  be  filled  with  scrap  gold  or 
solder. 

While  iridio-platinum  wire  of  a  suitable  size  will  usually  meet  all 
of  the  requirements  of  a  dowel,  one  constructed  in  this  manner  possesses 
the  advantage  of  being  largest  at  the  junction  hctzvcen  crozvn  and  root 
which  is  of  course  the  weakest  point  in  the  attachment  of  any  kind  of  a 
dowel  crown;  and  the  use  of  such  a  dowel  may  be  especially  indicated 
in  those  cases  where  the  canal  has  become  abnormally  enlarged  from  decay. 

When  the  cap  has  been  completed  and  finished, 

Tmprcssitn  and  adjusted  to  its  proper  position  on  the  root,  the 

and"BltC."  usual    impression   should   then   be    taken    in   plaster, 

and  this  preceded,  whenever  necessary,  by  a  "bite" 

in  wax. 

After  securing  the  impression,  it  should  be  observed  that  the  cap 
rests  firmly  in  place  in  it,  and,  if  necessary,  it  should  be  sealed  with  hot 
wax.  The  interior  of  the  band  and  surface  of  the  dowel  should  then  be 
covered  with  a  thin  film  of  melted  wax,  to  facilitate  its  removal  from, 
and  admit  of  its  accurate  readjustment  to,  the  model. 


^30 


This  is  of  paramount  importance  in  this  class  of  work,  because  of 
the  necessity  for  frequently  trying  to  place  on  the  model  during  the  con- 
struction of  the  crown,  and  particularly  in  those  cases  requiring  a  resto- 
ration of  occlusion. 

The   facing   should  be    selected    in    accordance 
Tacing.  with  the  requirements  of  color  and  size,  and  ground 

to  conform  with  the  desired  shape  and  character- 
istics. As  the  color  is  more  likely  to  be  slightly  bleached  instead  of  be- 
coming darker,  if  any  variation  is  necessary  or  unavoidable,  it  should 
invariably  be  darker  than  lighter,  though  the  best  makes  of  porcelain 
teeth  rarely  change  to  any  appreciable  extent  if  the  proper  make  and 
color  of  "body"  is  placed  back  of  them,  and  properly  fused. 

In  this  connection,  it  is  necessary  to  use  a  "body"  the  fusing  point 
of  which  will  not  affect  the  color  of  the  facing,  as  an  example  of  which 
the  use  of  the  higher  fusing  American  "bodies"  in  combination  with  the 
English  make  of  facings  will  entirely  destroy  the  color  of  the  latter. 


Ct: 


d 


In  grinding  the  facing,  the  edge  of  the  cap  should  previously  be 
nicely  rounded  with  disks  (Fig.  183,  A),  and  the  cervical  end  of  the 
facing  then  ground  thin  to  admit  of  overlapping  upon  the  labial  or  buccal 
edge  of  the  band  without  causing  imdue  prominence  at  this  point.  (Fig. 
183,  B.) 

This  is  necessary  as  a  means  of  bringing  the  edge  of  the  facing  into 
close  proximity  with  the  gum,  and  for  the  purpose  of  thus  affording  a 
mechanical  retention  to  the  porcelain  with  which  this  portion  of  the  band 
should  invariably  be  completely  covered. 

If  the  platinum  band  is  not  entirely  covered  upon  this  surface,  it 
will  always  show  through  the  thin  transparent  tissue,  and  occasion  the 
presentation  of  a  dark  blue  line,  at  this  point. 

As  this  is  a  decidedly  inartistic  and  undesirable  feature,  and  as  there 
is  no  physical  union  betzveen  porcelain  and  platinum,  the  overlapping  of 
the  facing  affords  a  secure  mechanical  retention  for  a  sufficient  quan- 
tity of  porcelain  to  cover  this  portion  of  the  band  and  overcome  this  pos- 
sible objection,  and  result  in  a  smooth  flush  joint  in  the  finished  crown. 


231 

Wherever  it  is  desirable  to  retain  porcelain  in  contact  with  platinum, 
some  similar  means  of  affording  mechanical  retention  is  always  neces- 
sary, and  this  may  be  further  facilitated  by  allowing  a  very  slight  space 
to  exist  between  facing  and  cap.     (Fig.  183,  C.) 

When  the  facing  has  been  thus  properly  adapted,  it  should  be  sealed 
to  place  on  the  cap  with  adhesive  wax,  and  the  whole  then  detached 
from  the  model  and  invested. 

In    investing,    only   enough  material   should   be 

TltPestment  used  to  surround  the  crown  nicely  and  afford  sufft- 

cient  strength  in  the  investment ;  and  when  the  ma- 
terial has  crystallized,  all  surplus  should  be  trimmed  away  until  the 
entire  lingual  surface  of  the  facing  is  freely  exposed.    (Fig.  184.) 

This  free  exposure  is  necessary  as  a  means  of  facilitating  the  solder- 
ing, and  it  may  be  made  without  increasing  the  danger  of  fracturing  the 
facing,  if  the  case  is  then  adequately  heated  before  attempting  to  solder. 


Ficj,ld4. 


Before  heating  the  case  the  pins  should  be  bent 
Soldering  Taclng.  dozvn  toward  the  porcelain  until  their  ends  may  be 
brought  into  absolute  contact  with  the  metal  parts. 
This  may  be  done  by  holding  the  facing  firmly  in  place  with  a  blunt- 
pointed  instrument  in  one  hand,  to  prevent  displacing  it,  while  another 
instrumcrit,  held  in  the  other  hand,  may  be  placed  against  the  extreme 
ends  of  the  pins  and  sufficient  pressure  applied  to  bend  them  into  the 
desired  relation. 

\\'hile    it    is    always    desirable    to   get    the   pins 
Hntcrlor  Crowns.       down  close  to  the  facing,  and  thus  make  more  room 
for  the  porcelain,  and  still  have  an  equal  degree  of 
strength  in  their  atlachmcnt,  this  is  especially  indicated  in  the  construc- 
tion of  anterior  crowns. 

In  these  crowns   the  pins   should  be  bent   down  close  to  the  porce- 
lain,  and  their  ends  brought   into  contact  with  the   surplus  end  of  the 


232 

dowel  at  a  point  as  close  to  the  Hoar  of  the  cap  as  possible  (Fis^.  185,  A), 
or  in  direct  contact  with  the  floor  itself.     (Fig.  185,  B.) 

This  is  important,  because  it  affords  opportunities  for  the  same  de- 
gree of  strength  in  their  union  with  the  cap,  and  yet  adds  to  that  of  the 
crown  by  getting  the  metal  parts  out  of  the  way,  so  that  they  will  not 
divide  the  porcelain  through  the  center,  or  interfere  with  the  proper  and 
desired  contour  of  the  lingual  surface. 

In  cases  where  the  ends  of  the  pins  will  not  reach  to  the  floor,  or 
dowel,  the  space  between  them  and  the  floor,  after  being  bent  down  to- 
ward the  porcelain,  may  be  filled  in  with  one  or  two  thicknesses  of 
platinum  plate,  or  wire,  if  necessary,  until  continuous  contact  may  be 
secured,  as  illustrated  in  Fig.  185,  C.  The  finished  crown,  showing  the 
oossibilities  of  contour,  strength  and  artistic  effect,  is  illustrated  in  Fig, 
185,  D. 


u 


fj<j.  185, 


As  there  is  no  physical  union  between  porcelain 
Bicuspid  CfOWns.  and  platinum,  in  the  construction  of  bicuspid 
crowns,  it  is  not  only  desirable  to  make  as  much 
space  for  the  porcelain  which  is  to  form  the  entire  lingual  surface  of  the 
crown,  as  possible,  but  it  is  also  often  necessary  to  provide  some  means 
for  supporting  it  against  any  possible  line  of  cleavage,  in  order  to  pre- 
clude subsequent  fracturing  of  this  mass  of  porcelain  from  the  stress  of 
mastication. 

This  support  to  the  porcelain,  and  destruction  of  any  line  of  cleav- 
age, may  be  best  and  most  easily  accomplished  by  soldering  a  narrow 
banrl  of  platinum  about  one-sixteenth  of  an  inch  wide  to  the  floor  of  the 
cap,  even  witli  tlie  qA^g:  of  the  band.  This  should  be  fitted  before  heating 
the  case,  and  may  be  attached  at  the  time  of  soldering  the   facing,  and 


233 

its  presence  thus  forms  a  cup-shaped  support  which  admirably  answers 
the  purpose  for  which  it  is  intended,     (hig-  i86,  A.) 

Another  means  of  accomphshing  the  same  end  has  been  suggested 
by  Dr.  Capon,  and  consists  in  adapting  and  attaching  the  floor  to  the 
inside  of  the  hngual  surface  of  the  band,  thus  allowing  the  occlusal  edge 
to  project  about  one-sixteenth  of  an  inch  beyond  the  floor.  This  method 
retains  and  supports  the  porcelain  in  the  same  manner,  but  is  much  more 
diflicult  to  adapt,  and  consumes  considerably  more  time. 

The  same  result  was  previously  sought  by  attaching  a  small  vertical 
extension  of  round  plafiimm  wire  to  the  immediate  center  of  the  lingual 
portion  of  the  cap.  (Fig.  i86,  B.)  Or,  when  two  dowels  were  used,  the 
surplus  end  of  the  lingual  one  was  thus  employed.     (Fig.  i86,  C.) 

Excepting  in  the  latter  instance,  this  is  somewhat  difficult  to  hold  in 
its  proper  place  while  soldering,  and  may  prove  an  element  of  weakness 


Ficj.  186. 


instead  of  strength, 
sons  such  methods 
now  to  be  regarded 
often    indicated   on 
The  finished  crown 

molar  Crowns. 

in  the  construction 
building  the   entire 

lUitb  Taciti9. 

whenever  possible, 
visible  parts  of  the 


if  not  properly  adjusted.     For  these  important  rea- 

have  practically  been  abandoned,  and  the  former  is 

as  the  typical  and  ideal  type  of  construction,  and  is 

mcisors,    cuspids   and   molars   as   well   as   biscuspids. 

is  illustrated  in  Fig.  i86,  D. 

In  the  construction  of  molar  crowns,  tivo 
methods  are  employed.  One  consists  in  using  a  fac- 
ing and  observing  similar  details  to  those  indicated 
of  bicuspids,  and  the  other  in  making  the  cap,  and 
crown  of  porcelain  without  a  facing. 

While  it  is  true  that  the  requirements  of  color 

are  not  quite  so  important  in  molars,  tlie  best  results 

will  usually  be  obtained  from  the  use  of    a    facing 

for  Ihe  reason  that  both  the  form  and  color  of  the 

crown  are  obtained  and  preserved  in  the  facing. 


234 

When  a  facing  is  used,  the  construction  should  be  made,  as  indi- 
cated for  bicuspid  crowns,  and  illustrated  in  Fig.  187,  A,  and  Fig.  187, 
B  shows  the  finished  crown. 

In  very  close  "bites"  the  use  of  a  facing  may 
UlitbOUt  Tacing.        often  be   contraindicated,  and  the    best    results  ob- 
tained by  simply  making  the  cap  and  forming  the 
entire  crown  with  porcelain.    For  such  cases  the  porcelain  should  be  sup- 
ported by  the  means  indicated  for  bicuspids,  which,  together  with  the 
finished  crown,  is  illustrated  in  Fig.  188. 


U 


Fic].l87. 


Additional  mechanical  means  for  obtaining,  or  aiding  in,  the  attach- 
ment of  the  porcelain  to  the  cap  may  also  be  secured  in  any  of  these  vari- 
ous styles  of  construction,  by  roughening  or  spurring  the  surface  of  the 
platinum  with  a  sharp-pointed  instrument.  This  latter  method  is  em- 
ployed exclusively  by  some,  and  may  serve  the  purpose  in  large  crowns. 


F/^./aa. 

where  considerable  surface   is  exposed,  without  being  supplemented  by 
any  of  the  former  means. 

Uariations  in  Construction. 

Because  of  the  acknowledged  advantages  of  a  band,  the  foregoing 
style  of  construction  has  been  given  precedence,  and  designated  as  the 
typical  one ;  yet,  while  it  is  true  that  crowns  so  made  are  perhaps  more 
universally  applicable,  and  productive  of  more  permanent  results,  it  is 
also  true  that  there  are  many  variations  of  methods  of  more  or  less  value, 
the  employment  of  many  of  which  may  be  frequently  indicated. 


235 

Kecnforccd  €ap$. 

As  inherent  strength  in  the  metal  parts  has  already  been  claimed  as 
a  prerequisite  in  this  work,  one  of  the  most  useful  variations  in  the  con- 
struction is  to  be  obtained  by  reenforcing  the  cap  in  a  manner  similar  to 
that  previously  recommended  in  the  construction  of  crowns  with  the  so- 
called  saddle-back  teeth. 

Such  a  procedure  imparts  to  the  finished  porcelain  crown  a  degree 
of  strength  which  is  appreciably  valuable  in  many  cases ;  particularly  in 
bicuspid  crowns,  and  in  those  cases  where  the  crown  is  not  supported  by 
adjacent  teeth  on  one  or  both  sides,  and  where  the  absence  of  some  of 
the  opposing  teeth  necessitate  more  than  average  occluding  stress. 

This  increased  strength  may  be  secured  by  allowing  the  floor  to  pro- 
ject slightly  beyond  the  band  upon  the  approximal  and  lingual  surfaces, 
and  then  filling  in  the  shoulder  so  formed  with  platinum  solder  until 
smooth  and  flush.    The  additional  thickness  of  a  cap  so  made  further  pre- 


C 


eludes  the  possibility  of  subsequent  irritation  to  the  surrounding  tissue  b> 
affording  a  heavier,  smoother  and  more  rounding  edge.     (Fig.  189,  A.) 

Since  the  pins  of  a  facing  may  be  an  element 
Grinding  Off  of  weakness  in  a  finished  crown  in  those  cases  where 

""'*•  the   natural   crowns   are   very    short,    or   where   the 

artificial  crown  must  be  very  tliin  in  order  to  ac- 
commodate the  occlusion  of  the  opposing  teeth,  it  may  become  necessary, 
or  desirable,  to  cut  them  off  close  to  the  surface  of  the  facing. 

In  such  cases  this  may  be  done  without  materially  diminishing  the 
strength  of  the  finished  crown  b}-  so  shaping  the  projecting  surplus  end 
of  the  dowel  as  to  have  it  mechanically  retain  both  facing  and  body. 

In  this  procedure  the  pins  may  be  used  to  sustain  the  relation  of 
the  facing  to  the  cap  until  after  the  Urst  bake,  when  they  may  be 
ground  oft"  close  and  the  crown  then  completed.     (Fig.   i8g,  B.) 

Another   variation   applicable   to   similar   condi- 
Ceaving  Pins  tions  consists  in  bending  the  pins  down   until  their 

€xpo$(d.  ends  come  in   contact   with   the  floor,  and  then   fill- 

ing in  between  them  with  platinum  solder,  and  sub- 
sequently making  no  effort  to  cover  them  with  porcelain.    (Fig.  189.  C.) 


236 
lUtttiout  Band. 

That  style  of  construction  which  involves  simply  the  adaptation  of 
a  metal  floor  or  base  to  the  end  of  the  root,  and  the  attachment  of  a  dowel 
and  facing  thereto,  and  which  has  previously  been  designated  as  the 
"plate  and  dowel"  crown,  is  equally  as  applicable  to  porcelain  work  as 
to  gold  work. 

The  indications  and  general  principles,  and  the 
Procedure.  detail  of  procedure  incident  to  the  requirements  of 

root  preparation,  and  the  construction  of  the  base 
of  the  crown,  are  identically  the  same  as  previously  outlined.  The  only 
exception  is  the  variation  w^hich  the  completion  of  the  crown  with  porce- 
lain "body"  instead  of  gold  solder  demands,  and  which  includes  the  use 
of  platinum  and  high-grade  solder. 


Ficj.  190. 


Wherever  a  band  is  not  desirable,  for  any  rea- 

PlatC  and  Dowtl.       son,  or  where  its  use  may  be  contraindicated,  and  the 

preference  given  to  this  style  of  construction,  a  plate 

of  platinum  about  36  gauge  should  be  adapted  to  the  end  of  the  root,  by 

burnishing  or  swaging,  as  indicated  in  Chapter  X. 

The  dowel  should  then  be  soldered;  the  cap  again  adjusted  to  the 
root,  and  reburnished  and  properly  trimmed  around  the  edge,  the  models 
secured,  and  the  facing  attached  by  observing  the  requirements  indicated 
in  the  immediately  preceding  style  of  construction,  as  are  consecutively 
illustrated  in  Fig.  190.  If  the  presence  of  this  thin  plate  of  platinum 
should  be  objectionable  or  conspicuous,  it  may  be  afterward  removed 
by  destroying  its  attachment  to  the  dowel  with  a  small  round  bur,  care- 
fully inserting  the  edge  of  a  thin  knife  blade  between  it  and  the  porcelain 
on  the  lingual  surface,  and  gently  lifting  it  away  from  the  base  of  the 
crown.  A  slight  deepening  of  the  canal,  or  shortening  of  the  dowel,  will 
allow  for  its  absence,  and  admit  of  placing  the  crown  in  close  proximity 
with  the  root. 


237 

Partial  Bands. 

The  employment  ol  a  partial  band  encircling  only  the  approximal 
and  ling-ual  sides  of  the  root,  as  a  means  of  increasing  the  stability  of 
the  attachment  of  the  crown,  may  also  be  made  in  a  manner  similar  to 
that  already  mentioned. 

As  this  style  of  construction  serves  to  fortify  the  crown  against  stress 
in  the  direction  in  which  it  is  usually  imposed,  and  also  renders  this  por- 
ton  of  the  joint  between  crown  and  root  more  or  less  immune  to  the 
penetration  of  secretions,  it  at  once  recommends  itself  as  a  useful  practice, 
especially  indicated  on  the  six  anterior  teeth,  where  the  root  is  allowed 
to  project  slightly  beyond  the  gum  line  on  the  lingual  side. 


A 


Fi<iJ9L 


The  effect  of  a  partial  band  to  serve  such  pur- 

Proccdurc.  poses  may  be  obtained  with   the  greatest  degree  of 

facility  by  allowing  a  sufficient  surplus  of  the  plate 

to  extend  beyond  the  root  on  this  surface,  until  the  adaptation  of  ihe  base 

has  been  secured,  and  the  dowel  soldered. 

The  cap  may  now  be  adjusted  to  position  on  the  root,  where  it  is 
held  firmly  by  the  presence  of  the  dowel,  and  this  surplus  edge  then  bur- 
nished up  close  to  the  surface  of  the  root,  and  finally  trimmed  to  follow 
the  curvature  of  the  gum. 

A  surplus  sufficient  to  admit  of  reaching  the  gum  line,  and  passing 
just  a  bit  beneath  it,  should  always  be  allowed  to  remain,  and  if  the 
accurate  burnishing  of  this  upturned  edge  is  made  difficult  because  of 
the  length  of  the  root,  a  slight  incision  through  ihc  surplus  edge  of  the 
plate  at  the  center  of  the  lingual  surface  will  facilitate  the  possililc  adapta- 
tion. This  may  be  subsequently  soldered,  either  before  or  after  the  im- 
pression has  been  taken,  but  should  always  be  done  before  the  porcelain 


238 

is  applied.     More  than  one  incision  may  be  sometimes  indicated,  and  are 
permissible  when  necessary. 

The  various  steps  in  this  style  of  construction  are  consecutively  illus- 
trated in  Fig.  191. 

3iicRet  €rown$. 

The  principles  involved  in  the  so-called  "jacket"  style  of  crown  con- 
struction, as  applied  to  both  gold  and  porcelain  work,  have  been  else- 
where considered,  together  with  the  indications,  advantages  and  disad- 
vantages governing  their  application. 

The  practicability  of  these  crowns,  however,  when  made  in  com- 
bination with  porcelain,  is  apparently  a  question  of  much  dispute,  and 
has  continued  to  be  since  the  method,  which  was  the  primitive  effort  in 
the  line  of  constructing  porcelain  crowns  in  combination  with  platinum, 
was  first  suggested  by  Dr.  C.  H.  Land. 

The  advocates  of  this  style  of  construction  claim  that  it  is  more  or 
less  universally  indicated  in  restoring  the  crowns  of  the  six  anterior  teeth, 
upper  and  lower ;  and  that  the  principal  advantage  lies  in  the  conservation 
of  tooth  structure,  and  the  preservation  of  the  pulp. 

While  both  of  these  considerations  are  always  of  material  significance 
to  the  conscientious  operator,  and  should  be  observed  wherever  possible, 
still  they  do  not  constitute  the  complete  maximum  of  requirements  of 
crown  construction  and  application,  even  when  combined  with  the  highest 
esthetic  possibilities,  because  the  requirement  of  strength  is,  of  course, 
of  equal  importance,  having  so  great  an  influence  upon  the  serviceability 
and  permanency  of  the  work. 

In  view  of  this  fact,  and  also  that  the  projecting  end  of  the  crown 
of  the  natural  tooth,  which  is  to  be  telescoped  by  the  cap  or  "jacket,"  as 
a  means  of  affording  attachment  for  the  artificial  crown,  is  allowed  to 
remain,  or  is  preserved,  at  the  expense  of  the  thickness  of  porcelain  which 
may  be  subsequently  used  in  the  construction  of  the  crown ;  and,  because 
of  the  friable  nature  of  porcelain,  particularly  when  used  in  small  quan- 
tity, this  style  of  construction  is  not  to  be  recommended  as  a  general  or 
conservative  practice,  and  is  by  no  means  universally  applicable,  if  the 
most  permanent  results  are  desired. 

In  this  connection,  it  seems  more  than  probable  that  a  large  per- 
centage of  the  early  failures  which  marked  the  advent  of  the  porcelain 
crown  constructed  for  the  individual  case,  and  retarded  the  development 
of  this  work,  may  be  attributed  as  much  to  the  method  of  construction  as 
to  the  use  of  the  loiv  fusing  bodies,  which  were  formerly  employed. 

Aside  from  the  inherent  weakness,  which  a,deqqate  accommodation 


239 

for  the  root  in  the  body  of  the  crown  demands,  the  artistic  possibilities 
are  also  often  somewhat  hampered  by  the  more  or  less  clumsy  appear- 
ance of  the  finished  crown. 

Whenever  an  adequate  length  of  the  adjacent 

Tndications  for        teeth,  and  a  favorable  occlusion,  will  admit  of  over- 

Porcdailt  Jackets,      coming  these  objectionable  features,  and  securing  a 

maximum  degree  of  strength,  jacket  crowns  may  be 

constructed     with    porcelain,    producing     serviceable     and     artistic 

restorations. 

In  the  application  of   this   style  of  crown,  the 
Procedure.  remaining  natural  crown  should  be  favorably  shaped 

to  admit  of  the  accurate  adaptation  of  the  jacket,  and 
of  the  proper  alignment  of  the  facing,  as  indicated  in  the  previous  con- 
sideration, and  illustrated  in  Fig.  192,  A. 


^ 


it 


The  measurement  should  be  taken  and  a  band  of  about  36  gauge 
platinum,  wide  enough  to  encompass  the  entire  remaining  natural  crown, 
then  made.  The  overlapping  of  the  ends  in  this  instance  is  not  always 
advisable,  because  of  the  impediment  offered  to  the  burnishing  by  such 
additional  stiffness. 

When  this  has  been  accurately  trimmed  and  fitted  at  the  cervical 
edge,  a  cut  in  each  approxinial  side  of  the  band,  beginning  at  the  incisal 
and  extending  well  toward  the  cervical  edge,  will  facilitate  the  subsequent 
burnishing  of  the  platinum  into  a  close  conformation  with  the  root.  A 
blunt  piece  of  wood  and  a  light  mallet,  or  a  smooth  foot-plugger  in  an 
automatic  mallet  may  be  found  useful  in  this  procedure,  but  care  should 
be  exercised  to  avoid  drawing  the  cap  down  from  its  proper  cervical 
relation. 

The  edges  should  now  be  pinched  together  with  pliers  around  the 
incisal  end  of  the  root  until  in  close  contact,  the  cap  then  removed,  the 
surplus  trimmed  away,  and  the  joints  soldered.     Pure  gold  will  answer 


240 

nicely  for  this  purpose,  if  used  sparingly  and  properly  fused,  though  plati- 
num solder  is  preferable. 

Platinum  foil.  No.  60  or  120,  may  often  be  used  in  securing  the 
proper  adaptation  around  the  cervix,  and  slightly  beneath  the  free  mar- 
gin of  the  gum,  to  which  point  it  should  be  carried,  because  of  the  greater 
facility  with  which  it  may  be  even  more  closely  adapted;  and  extreme 
thinness  of  the  cap,  on  the  labial  surface,  at  least,  is  also  advantageous 
to  the  subsequent  adjustment  of  the  facing.  In  the  use  of  the  foil,  how- 
ever, when  the  proper  adaptation  has  been  secured  by  burnishing,  with 
the  surplus  overlapped  upon  the  approximal  and  lingual  surfaces,  the 
cap  should  then  be  slightly  re-inforced  with  platinum  solder,  or  pure  gold 
thoroughly  fused. 

The  best  results  are  doubtless  to  be  obtained,  as  a  general  practice, 
from  the  use  of  the  heavier  cap,  and  while  pure  platinum  is  not  as  soft 
and  malleable  as  pure  gold,  if  the  piece  is  well  annealed  in  the  porcelain 
furnace,  as  recommended,  no  great  difficulty  will  be  experienced  in  adapt- 
ing platinum  of  36  gauge  to  the  requirements  of  these  cases.  If  prefer- 
able, the  adaptation  may  be  secured  by  taking  an  impression  of  the  end 
of  the  root,  making  dies  and  swaging,  as  previously  described. 

The  entire  surface  of  the  cap,  however  made  (Fig.  192,  B),  should 
now  be  slightly  roughened  with  a  sharp  chisel,  or  other  convenient  instru- 
ment, to  facilitate  the  attachment  of  the  porcelain,  and  the  impression 
taken  with  it  in  position  on  the  root.  Before  filling  the  impression,  the 
cap  should  be  filled  with  wax  to  facilitate  its  subsequent  removal  from 
the  model. 

A  very  tJiin  facing  (Fig.  192,  C)  of  the  proper  size  and  color  should 
now  be  selected  and  ground  to  its  proper  adjustment.  This  sometimes 
requires  that  the  entire  lingual  surface,  including  pins,  be  ground  away 
until  only  a  very  thin  veneer  remains,  but  it  is  best  to  allow  the  pins  to 
remain  also,  if  possible,  because  of  the  advantage  to  be  derived  from 
their  presence  in  securely  sustaining  the  relation  of  the  facing  to  the  cap, 
by  bringing  them  in  contact  and  soldering,  previous  to  applying  the  por- 
celain.    (Fig.  192,  D.) 

Where  it  becomes  necessary  to  grind  the  pins  away  entirely,  the  dif- 
ficulty of  sustaining  the  veneer  in  its  relation  to  the  cap  during  the  appli- 
cation and  fusing  of  the  "body"  is,  of  course,  increased,  and  extreme  care 
is  necessary  in  heating  the  case,  because  of  the  possible  expansion  incident 
to  too  rapid  heating;  and  in  fusing,  because  of  the  shrinkage,  each  of 
which  may  result  in  a  displacement. 

This  procedure  may  Ijc  facilitated  by  first  covering  the  cap  with  a 
thin  layer  of  "body"  and  fusing  it  until  the  particles  are  well  coalesced, 
without  presenting  a  gla7xd  surface.     This  then  admits  of  a  more  ready 


241 

and  secure  attaoliment  of  the  veneer  to  the  cap  by  holding  it  in  place 
and  packing  thinly  mixed  body  into  the  space  between  it  and  the  cap, 
until  it  is  retained  in  position  by  the  adhesive  properties  of  the  body  after 
the  moisture  has  been  evaporated,  when  it  is  ready  for  the  final  attachment 
to  be  obtained  by  the  fusion  of  the  porcelain.  Fig.  192,  E,  illustrates  the 
finished  crown, 

A  method  of  veneering  platinum  and  gold 
Uarifltion  of  method,  crowns  constructed  in  the  ordinary  manner,  excepting 
that  the  dimensions  are  reduced  enough  to  admit  of 
the  presence  of  a  covering  of  porcelain,  which  is  retained  in  contact  with 
the  metal  by  roughening  the  surface,  is  recommended  by  Dr.  George  Evans 
and  others,  as  a  means  of  securing  the  presentation  of  a  more  esthetic 
effect,  combined  with  the  advantages  of  a  metal  crown. 

As  thill  layers  of  porcelain,  whether  of  the  high  or  low  fusing  variety, 
do  not  possess  strength,  and  as  tlicrc  is  no  physical  or  molecular  union 
betzveen  porcelain  and  platinum,  or  gold,  the  method  is  not  considered  to 
be  a  safe  or  reliable  one. 

Cbe  Spauiaina  Jill  Porcelain  Crown. 

That  which  seems  to  be  the  ideal  method  of  constructing  a  "jacket 
crown"  has  been  suggested  and  is  practiced  extensively  by  Dr.  E.  B. 
Spaulding,  of  Detroit,  INIich.  In  this  type  of  construction  the  presence 
of  a  platinum  cap  in  the  completed  crown  is  avoided,  and  thus  this 
clement  of  inherent  weakness  is  eliminated.  Hence,  even  though  the 
finished  crown  is  but  a  shell  of  porcelain,  it  is  stronger  than  the  former 
style,  wherein  a  thin  platinum  cap  remains  as  an  integral  part  of  the 
crown ;  and  when  this  "shell  of  porcelain"  is  properlv  and  skilfully 
adapted,  and  then  supported  by  the  mounting  medium,  it  seems  to  offer 
every  opportunity  for  obtaining  the  highest  possibilities  in  the  line  of 
combined  esthetic  and  mechanical  requirements.  Dr.  Spaulding  describes 
his  method  as  follows : 

The  following  process  in  detail  iov  preparing  the 
tCChniOUC  tooth,  forming  matrix.  a(la]iting  veneer  and  fusing,  I 

Of  All -Porcelain        have  adopted  after  considerable  experiment  and  prac- 
tice, as  being  the  most  simple,  direct  and  accurate 
means  of  producing  a  uniformly  successful  result. 
Let  us  first  look  at  Figs,  i  and  2,  Plate  A,  to  get  a  better  idea  of 
what  it  is  we  wish.     Fig.   I   shows  a  tooth  properly  prepared,   enamel 


242 

removed  to  the  shoulder  at  the  g'um  line  and  dentine  more  or  less  cone 
shaped.  Its  shell  of  porcelain  is  seen  above,  and  when  in  place  on  the 
tooth  fits  as  nicely  as  shown  in  Fig.  2,  joint  everywhere  flush  and  almost, 
if  not  quite,  as  tight  as  an  inlay  joint. 

When  a  tooth  in  the  mouth  calls  for  treatment  in  this  manner  it  is 
usually  because  of  deficient  enamel ;  consequently  there  is  not  the  large 
amount  of  enamel  to  remove  which  would  be  found  on  a  normal  or 
perfect  tooth. 

We  will  imagine  an  upper  central  incisor,  the  enamel  of  which  is 
lacking  on  the  labial  surface  from  erosion,  and  we  desire  to  remove  the 
remainder  of  the  enamel,  preparatory  to  making  a  porcelain  jacket. 

We   first  take   a   />^-inch,  thin,   separating  car- 
niCthOd  borundum  disk  (rubber  and  carborundum),  mounted 

of  KcmovlltQ  ill  the  engine  hand  piece  and.  being  revolved  at  a  high 

Enamel,  speed  and  kept  wet  with  a  stream  of  warm  water 

from  the  syringe  in  the  hands  of  an  assistant,  the 
mesio-approximal  surface  is  removed  in  the  manner  indicated  in  Fig.  3. 
Commence  at  the  cutting  edge  and  move  the  disk  toward  the  cervix. 
Where  the  disk  is  stopped  at  the  gum,  a  shoulder  is  left  such  as  is  desired 
around  the  entire  tooth  when  the  preparation  is  completed,  and  this 
shoulder  should  be  at,  or  slightly  below,  the  gum  line. 

The  disto-approximal  surface  is  dressed  in  like  manner  and  the  re- 
maining enamel  removed  from  the  labial  and  lingual  surfaces  by  means  of 
a  5^-inch  knife-edge  carborundum  stone  (not  disk).  This  removes  the 
enamel  from  four  sides  and  leaves  four  corners  to  be  rounded  off  by 
means  of  the  disk  again,  approached  at  different  angles. 

Up  to  this  point  we  have  paid  little  attention  to  the  shoulder  except  as 
left  by  the  disk  on  the  approximal  surfaces.  By  the  use  of  the  smallest 
inverted  carborundum  stones  on  the  market  (3/16  inch.  No.  184,  Lee, 
Smith  &  Sons)  mounted  with  shellac  on  an  old  bur,  the  shoulder  on  the 
labial  surface  is  partially  dressed,  and  a  similar  stone  mounted  on  a  right 
angel  hand  piece  bur,  accomplishes  the  same  result  on  the  lingual  surface. 
The  shoulder  is  finished  and  receives  its  definite  line  by  means  of  sharp 
wheel  burs.  Let  the  use  of  new,  sharp  knife-edge  stones  and  nciv,  sharp, 
wheel  burs  be  emphasized,  for  a  dull  bur  and  a  dull  stone  both  cause  pain. 
The  point,  or  cutting  edge  of  the  tooth,  is  shortened  and  the  whole  treated 
with  a  few  quick  touches  with  a  sand-paper  disk  to  smooth  and  complete 
the  preparation  of  the  tooth  to  receive  the  matrix.  For  convenience,  we 
will  call  the  prepared  portion  of  the  tooth  the  conical  portion. 


243 


FIG     6 


244 

In  preparing  the  tooth  in  this  manner  we  have  not  encroached  upon 
the  pulp  at  all,  and  what  would  seem  to  be  an  excruciatingly  painful  opera- 
tion is  really  little  more  annoying  than  the  preparation  of  cavities,  as  we  do 
almost  every  day. 

The  first  step  in  forming  the  matrix  is  to  obtain 
Tormina  ^'^^  circumference  of  the  tooth  over  the  shoulder  and 

the  matrix.  under  the  gum.     This  is  done  by  means  of  a  denti- 

meter,  or  by  a  thin  strip  of  copper  or  other  metal 
pinched  about  the  tooth.  This  measurement  is  more  conveniently  taken 
before  the  tooth  is  prepared  and  the  shoulder  formed. 

Now  cut  a  piece  of  inlay  platinum  (i/iooo  inch)  1/16  inch  longer 
than  the  measurement  taken  and  ^  inch  broader  than  the  length  of  the 
conical  portion  of  the  tooth  from  the  shoulder  to  the  point.  This  rec- 
tangular piece  of  platinum,  as  shown  in  Fig.  4,  is  now  changed  by  cutting 
off  the  angles  "A"  and  "B"  to  the  form  C,  E,  F,  D,  Fig.  5.  The  edges  C, 
E,  and  D,  F,  are  lapped  1/32  part  of  an  inch,  the  cone  shaped  instrument, 
Fig.  6,  assisting  to  bring  the  edges  of  the  platinum  in  absolute  contact, 
which  is  then  firmly  held  in  the  pliers  (Fig.  7)  while  the  end  of  the  seam 
is  soldered  with  a  very  small  particle  of  pure  gold.  As  soon  as  part  of  the 
joint  is  soldered,  loose  the  pliers  and  grasp  the  platinum  on  the  side  op- 
posite to  the  seam,  and  if  the  edges  are  in  absolute  contact,  there  is  suffi- 
cient gold  present  to  complete  the  union  of  the  edges  when  the  heat  is 
again  applied.  The  very  smallest  particle  of  gold  should  be  used  in 
soldering. 

Fig  8  (Plate  B)  shows  the  platinum  cone,  which  is  1/32  inch  larger  at 
its  base  than  the  circumference  of  the  tooth,  and  when  placed  over  the 
tooth,  will  slip  over  the  shoulder  and  under  the  gum. 

The  advantage  of  the  cone  is  now  shown  in  Fig.  9,  for  the  farther 
over  the  tooth  it  is  carried,  the  tighter  it  becomes  at  the  points  G  and  H, 
where  the  fit  of  the  matrix  innst  be  exact. 

Now,  with  a  piece  of  No.  27  gauge  copper  wire  in  the  dcntimcter,  a 
loop  is  placed  about  the  cone  (Fig.  10)  and  is  alternately  tightened  by 
twisting,  and  carried  toward  the  shoulder  with  a  burnishing  instrument 
until  the  wire  has  been  worked  carefully  into  the  angle  between  the 
shoulder  and  the  conical  portion,  carrying  the  platinum  with  it  and  shrink- 
ing it  to  the  tooth.  During  this  stage  of  the  process,  the  forefinger  of  the 
left  hand  has  been  held  tightly  on  the  point  of  the  cone  to  keep  it  firmly  in 
place.  The  wire  is  now  tightened  as  much  as  possible  without  breaking 
it,  and  serves  to  hold  the  platinum  firmly  while  the  next  stage  of  the 
burnishing  is  done. 


245 


H 


FIG. 8 


FIG.S 


FIG    lO 


'r^'  ■,.i,iiiii)>iii)jji)i)))i>n)n)j))iiii)iiiiiiijiii/j)j) 


FIG      11 


F  I  G.     11a 


FI  G    12 


FIG    14 


246 

The  burnishing  instrument  (Fig.  11)  is  made  from  a  bone  handle  of 
a  mouth  mirror,  and  its  shape  is  seen  in  the  illustration.  With  the  thumb 
and  forefinger  the  platinum  is  pinched  to  the  conical  portion,  aided  by  the 
burnisher  and  narrow  nosed  pliers,  or  tweezers,  so  that  the  surplus  is  car- 
ried to  the  approximal  sides  (Fig.  12,  I  and  J,  Plate  C).  Now  trim  the 
surplus,  leaving  an  extension  of  about  1/32  to  1/16  of  an  inch,  which  is 
lapped  over  and  burnished  down  smoothly  on  the  sides,  but  not  on  the 
point,  as  in  Fig.  13.  .The  wire  is  now  removed  and  the  platinum  thor- 
oughly burnished  over  the  shoulder  and  into  the  angle,  using  besides  the 
the  bone  burnisher  the  small  "V"  shaped  steel  burnisher  (Fig.  11  A). 
The  unburnished  point  of  the  matrix  (K,  Fig.  13),  is  now  grasped  in  the 
pliers  and  the  matrix  removed  and  replaced  once  or  twice  to  make  certain 
that  it  does  not  bind  at  or  below  the  shoulder.  This  done,  the  point  is 
lapped  and  burnished,  as  were  the  sides,  and  the  matrix  is  completed 
(Fig.  14). 

The  next  step  is  the  preparation  of  the  veneer, 

Preparation  which  forms  the  labial  portion  of  the  jacket. 

Of  the  The  proper  shade  and  shape  is  preferably  se- 

Porcelaln  Ueneer.  lected  in  a  vulcanite  tooth  on  account  of  its  shoulder 
(L,  Fig.  15),  which  assists  in  adjusting  to  the  matrix. 
The  back  and  pins  are  ground  away  until  a  very  thin  veneer  is  left,  as 
in  Fig.  10.  This  grinding  is  not  so  laborious  a  task  as  might  be  sup- 
posed if  small  knife-edge  carborundum  stones  are  used  together  with 
the  little  inverted  cone  stones  (No.  184)  previously  mentioned.  The 
•atones  should  be  kept  thoroughly  wet  during  the  grinding,  and  the  veneer 
tried  on  the  matrix,  which  is  in  place  on  the  tooth,  from  time  to  time,  in 
order  to  bring  it  to  proper  alignment  with  the  other  teeth.  When  it 
assumes  the  desired  position,  the  cervical  end  of  the  veneer  is  shortened, 
so  that  it  does  not  touch  the  shoulder,  as  at  M,  Fig.  17.  It  is  now  thor- 
oughly washed  to  removed  all  particles  of  carborundum,  and  adjusted  to 
position,  where  it  is  held  with  finger  of  left  hand  while  a  small  ball  of 
wax  (gutta  percha  base-plate  wax  preferred)  is  warmed  and  pressed 
against  the  lingual  portion  of  matrix  and  veneer,  imbedding  them  so  that 
they  are  held  in  their  proper  relation  (Fig.  18).  Usually  the  veneer  and 
matrix  are  held  firmly  enough  by  the  wax,  so  that  they  are  removed  from 
the  tooth  together,  but  if  they  should  separate,  the  wax  and  veneer  remain 
together  and  the  matrix  is  readily  teased  off  the  tooth  and  placed  in  its 
position  between  the  wax  and  the  veneer. 

Having  a  pair  of  tweezers,  with  sliding  band  for  locking  them,  place 
a  small  piece  of  vulcanite  rubber  on  one  beak ;  insert  the  bare  beak  within 
the  matrix  and  let  the  one  protected  with  the  rubber  rest  on  the  outside  of 


247 


..-■Si 


::^'L     k 


M 


FIG    15 


FIG.  16 


FIG.  17  FIG.J^e 


FIG.    19 


FIG.  ZO 


FIG.  21 


PLATE    C 


248 

veneer ;  close  and  lock.    Remove  the  wax,  and  the  matrix  and  veneer  will 
be  found  to  be  held  firmly  in  their  relative  position,  as  is  shown  in  Fig.  19. 

The  gutta  percha  base-plate  wax  (N,  Fig.  18)  is  not  excessively 
sticky,  and  is  black,  and  if  any  particles  remain  they  are  readily  seen  and 
removed  before  applying  the  porcelain  body.  O,  Fig.  19.  shows  how  the 
rubber  is  utilized  to  prevent  beak  or  pliers  from  slipping  on  surface  of 
veneer. 

The  body  is  first  applied  on  one  side,  only  at  the 
JIdding  the  Porcelain      point  indicated  by  the  arrow  P,  in  Fig.  19,  and,  being 
Body,  mixed  rather  thin  at  first,  the  tweezers  are  thoroughly 

jarred  by  drawing  across  them  a  rough  handled  in- 
strument until  the  moisture  is  seen  to  appear  on  the  opposite  side  of  the 
matrix,  corresponding  to  where  first  applied.  This  shows  that  all  the  air  be- 
tween the  matrix  and  veneer  has  been  driven  out  by  the  moist  body.  Now 
additional  body  is  applied  in  a  much  drier  state,  until  the  matrix  is  covered 
only  so  far  as  indicated  by  the  dotted  line  in  Fig.  19.  In  no  case  let  the 
body  reach  the  shoulder  before  the  first  fusing.  The  moisture  being  thor- 
oughly jarred  out.  the  work  is  ready  for  the  first  fusing.  Remove  the 
pliers,  when  the  matrix  and  veneer  will  be  found  to  be  held  firmly  by  the 
body  so  that  the  whole  will  stand  upright,  resting  on  the  base  of  the 
matrix,  and  is  carried  on  the  slab  into  the  furnace  in  this  manner.  At  the 
time  of  first  fusing  the  moisture  should  be  dried  out  slowly,  for  if  heated 
too  rapidly  the  moisture  between  the  matrix  and  veneer  will  form  steam 
and  throws  the  veneer  ofif.  Let  the  work  be  slowly  moved  into  the  fur- 
nace, so  that  the  veneer  faces  and  receives  the  heat  first. 

After  fusing,  place  the  united  veneer  and  matrix 
ReburniSbing.  on  the  tooth  and  the  portion  of  the  matrix  over  the 

shoulder  of  the  tooth  is  again  burnished  to  correct 
any  possible  changes  which  may  have  taken  place  during  previous  hand- 
ling. Removed,  and  again  washed,  the  matrix  is  completely  covered  with 
body  flush  to  the  shoulder  line  and  built  up  and  carved  on  the  lingual  and 
approximal  surfaces,  as  the  case  may  require.  There  may  be  as  many 
fusings  as  the  operator  deems  necessary  to  produce  the  desired  result. 
How  nearly  the  finished  article  resembles  the  shape  and  shade  of  a  natural 
tooth  must  depend  upon  the  operator's  knowledge  of  tooth  anatom}',  his 
artistic  eye  and  his  ability  to  manipulate  ])orcelain. 

Fig.  20  shows  shell  com])lete  before  matrix  is  removed.  The  matrix 
is  removed  much  as  it  is  from  an  inlaw  by  pulling  away  the  sides  with 
a  pair  of  tweezers,  care  being  used  not  to  let  them  slip  and  strike  the  edge 
of  the  shell  to  chip  it.    If  the  matrix  clings  very  closely  up  in  the  point,  it 


249 

is  readily  detached  with  a  small  bur  in  the  engine.     (See  Figs,  i  and  2  or 
shell  complete,  with  matrix  removed.) 

Before  setting  in  place  with  cement,  the  inside  of 
Setting.  shell  is  etched  with  hydrofluoric  acid,  to  provide  a 

surface  for  the  attachment  of  the  cement.  The  den- 
tine of  the  tooth  should  be  varnished  with  a  good  cavity  lining  before 
cementation.  The  cement  should  not  be  mixed  too  thin,  neither  should 
it  be  so  thick  that  much  force  is  necessary  to  carry  shell  to  place,  as  it 
might  be  fractured  in  this  way. 

A  question  which  will  readily  suggest  itself  is,  does  not  the  grinding 
out  of  the  porcelain  tooth  to  form  so  thin  a  veneer  change  its  color,  and 
also,  will  not  the  cement  change  its  shade  when  set  in  place?  That  is 
answered  by  saying  that  the  portion  of  the  porcelain  tooth  ground  away  is 
usually  yellow,  of  a  varying  shade,  and  the  characteristic  blue,  brown  or 
other  shade  is  retained  in  the  veneer,  and  when  a  cement  is  chosen,  a 
yellow  is  selected,  which  will  replace  the  underlying  yellow,  ground  away. 
It  is  possible  to  influence  the  shade  of  the  shell  somewhat  in  the  choice  of 
a  cement. 

By  the  completed  and  cemented  shell  we  have  a  live  and  healthy 
tooth,  thoroughly  protected  from  injurious  external  influences.  Experi- 
ence teaches  us  that  a  tooth  is  never  so  comfortable  with  a  metal  filling  or 
metal  crown  as  it  is  with  a  porcelain  inlay  or  porcelain  shell.  It  is  more 
artistic  and  natural  than  any  other  style  of  crown.  No  other  crown  has 
so  flush  and  tight  a  joint,  and  the  irritation  of  the  gum,  characteristic  of 
band  crowns,  is  entirely  absent. 

Lastly,  it  has  strength  to  withstand  severe  use  in  the  mouth.  As  a 
shell  uncemented  it  is  frail,  but  when  thoroughly  supported  by  cement  it 
has  the  endurance  almost  of  the  natural  enamel. 

The  porcelain  body  used  in  constructing  these 

m^^  shells  should  be  of  a  very  high  fusing  body,  or  what 

Porcelain  Body.        is  termed  block  body,  or  porcelain  tooth  body.    While 

the  Consolidated  high  fusing  body  will  answer  nicely, 

block  body  ma}-  be  prepared  by  taking  the  bicuspids  and  molars  of  a  set 

of  diatoric  (pinless)  teeth  and  pulverizing  them  in  a  wedge  wood  mortar. 

One  tooth  at  a  time  is  taken  in  the  mortar,  and  when  it  is  fractured  into 

a  number  of  small  pieces  thev  are  emptied  upon  a  sheet  of  white  paper 

and  an  assortment  made,  separating  the  pieces  composed  of  the  clear  blue, 

or  characteristic  color  of  the  cusps  of  the  tooth  from  the  remaining  yellow. 

which  forms  the  bulk  of  the  tooth.    The  blue  is  powdered  separately  from 

the  vellow.  and  the  amount  of  each  obtained  from  a  set  of  four  molars  and 


250 

four  bicuspids  gives  us  sufficient  body  of  these  two  shades  to  last  some 
time.  Four  shades  of  body,  two  blues  or  grays,  and  two  yellows,  are  usu- 
ally all  the  variety  needed  in  this  work  when  a  veneer  is  used.  This  very 
high  fusing  body  has  several  advantages  for  this  work  over  many  of  the 
so-called  high  fusing  bodies  found  on  the  market. 

First — The  body  is  of  exactly  the  same  material  as  the  veneer,  so  that 
when  completed  the  shell  is  of  one  grade  of  porcelain.  The  advantage  of 
this  is,  that  the  union  of  veneer  and  body  is  more  complete,  although,  the 
body  having  been  once  fused  and  refritted,  fuses  at  a  little  lower  tempera- 
ture than  it  did  the  first  time. 

Second — There  is  less  shrinkage. 

Third — There  is  not  the  liability  to  cracking  or  checking  upon  cooling 
that  there  is  when  a  lower  grade  of  body  is  used  in  connection  with  the 
veneer. 

Fourth — No  matter  how  many  times  the  work  may  be  fused,  there 
is  no  danger  of  its  becoming  porous  if  it  is  kept  absolutely  clean,  but  a 
lower  fusing  body  will  frequently  become  porous  when  fused  a  number  of 
times,  due  to  the  burning  out  of  the  flux  which  it  contains. 

What  is  known  as  lozv  fusing  (gold  matrix)  porcelain  has  no  place 
whatever  in  connection  with  this  work. 

"A"  (Fig.  21 )  is  a  plaster  model  of  a  typical  case  of  malformed 
enamel  due  to  impaired  nutrition  from  birth,  to  about  four  years  of  age. 

Model  "A"  was  made  in  June,  1902,  after  which  the  irregularity  of 
the  teeth  was  corrected,  and  in  July,  1903,  the  six  anterior  teeth  were 
covered  with  porcelain  by  the  process  just  described.  "B"  is  a  model  of 
the  case  after  it  was  completed.  Age  of  patient  at  completion,  nineteen 
years. 


Wit  of  tbe  Davis  and  togan  €rown$. 

Ready-made  porcelain  crowns,  such  as  the  Davis  and  Logan  designs, 
may  sometimes  be  employed  to  good  advantage  in  porcelain  work  for  the 
six  anterior  teeth,  by  combining  them  with  a  platinum  plate  or  cap,  as 
a  means  of  securing  accuracy  in  the  adaptation  and  permanency  in 
their  attachment  to  the  root. 

The  advantages  to  be  obtained  in  the  use  of  these 

JIdoantafiCS.  crowns  in  this  work  lie  in  their  artistic  form,  their 

unexcelled  strength,  and  the  greater  degree  of  trans- 

iucency  which  the  finished  crown  will  possess,  as  a  result  of  the  absence 


251 

of  an  additional  layer  of  either  metal  or  porcelain  placed  on  the  back  of 
the  original  crown. 

While  their  artistic  shape  is  not  to  be  disputed,  the  experienced  por- 
celain worker,  with  a  knowledge  of  tooth-form,  will  have  no  difficulty 
in  building  the  body  to  an  equally  artistic  outline,  where  a  facing  is  used, 
so  this  feature  is  to  be  seriously  regarded  as  a  consideration  only  as  a 
means  of  doing  without  the  knowledge,  and  avoiding  the  small  amount 
of  time  and  work  thus  involved. 

The  inherent  strength  of  the  porcelain  of  which  these  crowns  are 
made,  which  is  obtained  from  the  high  fusing  character  of  the  "body," 
and  from  its  then  being  properly  packed  and  fused,  is  doubtless  greater 
than  the  strength  of  the  porcelain  part  of  a  crown  constructed  with  a 
facing.  Hence,  this  feature  must  be  regarded  in  the  light  of  an  advantage 
of  importance,  and  yet,  where  a  simple  facing  is  used,  sufficient  strength 
may  ordinarily  be  obtained  by  securely  attaching  it  to  the  cap,  using  a 
high-grade  "body,"  and  properly  packing  and  fusing  it. 

The  greater  degree  of  translucency  is  indisputably  true,  and  consti- 
tutes an  advantage  of  inestimable  value  in  many  cases,  particularly  where 
the  color  is  extremely  difficult  to  match.  While  the  texture  of  an  ordinary 
facing  may  be  practically  the  same  as  that  of  these  crowns,  and  it  may 
primarily  possess  the  same  degree  of  translucency,  yet  this  important  fea- 
ture is,  nevertheless,  destroyed  to  some  extent  even  by  the  presence  of  a 
backing  of  porcelain,  of  nearly,  if  not  quite,  the  same  color.  This  is  due 
to  the  dividing  line  between,  and  the  difference  in  the  density  of,  the  two 
bodies. 

These  features  of  strength  and  translucency  are  so  important  as  to 
indicate  the  practicability  and  warrant  the  use  of  these  crowns  in  many 
cases,  perhaps,  in  preference  to  any  other  style  of  construction,  where  a 
good  selection  may  be  obtained. 

The  principal  disadvantages  lie  in  the  fact  that 

DisadPantagCS.  one  is  confined  to  a  more  or  less  limited  selection,  and 
that  the  opportunities  are  greater  for  securing  a  bet- 
ter choice  of  facings  than  of  crowns  because  of  the  latter  being  limited 
to  a  few  dozen  moulds,  as  compared  with  the  several  hundred  in  which 
the  facings  are  made ;  also  the  more  intricate  procedure,  and  greater  length 
of  time  consumed,  in  grinding  the  crown  to  a  proper  adjustment  and  rela- 
tion as  compared  with  the  facing. 

Because   of   the   greater   facility   with   which    a 

Jlpplication  Of         crown  with  a  separate  dow^el  may  be  adapted  to  the 
the  DaPiS  0row«.       root,    the    Davis    crown    will   be    found   particularly 
useful  and  applicable  to  this  style  of  construction. 
The  accompanying  dowel,  however,  is  useless,  and  must  be  replaced 


252 

with  one  of  iridio-platinum,  because  the  so-called  German  silver  alloys 
will  scarcely  withstand  the  degree  of  heat  necessary  to  subsequently  fuse 
the  porcelain,  and  the  latter  will  not  become  attached,  or  even  fuse  down 
close,  to  these  alloys. 

In  the  application  of  this  style  of  crown  with 

mill)  Band.  a  band,  the  root  should  be  prepared,  the  cap  made, 

the  dowel  attached,  and  the  impression  taken,  in  exact 

accordance  with  the  requirements  indicated  for  the  "band  and   dowel" 

style    of    construction    with    porcelain,    at    the    beginning    of    this 

chapter. 

When  the  model  has  been  secured,  the  cap  should  be  detached  there- 
from, then  replaced,  and  the  crown  selected. 

The  surplus  end  of  the  dowel  should  now  be  cut  away  until  only 
so  much  remains  as  will  be  accommodated  by  the  depth  of  the  countersunk 
cavity  in  the  crown,  and  the  latter  should  be  ground  to  the  proper  and 
required  adaptation  with  the  cap  and  the  adjacent  and  occluding  teeth. 


In  this  procedure  the  approximal  sides  should  be  ground  so  as  to 
admit  of  the  overlapping  of  the  labial  and  lingual  edge  of  the  crown  upon 
the  cap.  (Fig.  193,  A.)  This  is  essential  for  the  purpose  of  bringing 
the  edges  of  the  crown  into  close  proximity  with  the  gum  and  of  retaining 
the  porcelain  which  is  to  be  subsequently  applied  to  cover  the  band. 

Owing  to  the  shrinkage  of  porcelain,  it  is  impossible  to  get  enough 
body  between  the  crown  and  cap  in  the  first  or  primary  "bake"  to  com- 
pletely fill  the  space.  This  would  result  in  an  element  of  weakness,  of 
course,  in  the  finished  crown,  and  may  be  overcome  by  further  grinding 
away  the  approximal  surfaces  of  the  crown,  so  as  to  afford  opportunity 
for  the  admission  of  a  second  application  of  "body,"  which  may  fill  all 
crevices  caused  by  the  shrinkage  of  the  first.     (Fig.  193,  B.) 

When  the  grinding  of  the  crown  has  thus  been  completed,  it  should 
be  attached  to  the  cap  by  filling  the  countersunk  cavity  in  its  body  with 


253 

thin,  well  mixed  porcelain,  and  then  gently  forcing  it  to  place  while  on 
the  model.  The  latter  should  now  be  gently  tapped  with  an  instrument 
several  times  to  pack  the  porcelain  densely  around  the  dowel,  and  in  the 
space,  and  it  should  then  be  allowed  to  dry  until  all  of  the  moisture  is 
thoroughly  evaporated. 

The  crown  should  now  be  gently  removed  from  the  model,  adjusted 
to  a  proper  support,  and  given  the  primary  "bake,"  and  subsequently  the 
final  one,  in  accordance  with  the  requirements  which  will  be  considered 
later.     The  completed  crown  is  illustrated  in  Fig.  193,  C. 

When  it  is  desirable  to  construct  the  crown  by 

UlitbOUt  Band.         this  method  zvithout  a  hand,  the  foregoing  detail  is 

identical  zvith  the  requirements,  after  the  "plate  and 

dowel"  have  been  properly  adapted  to  the  root  and  the  impression  taken 


/7y.  19^. 


and  model  secured,  which  procedure  has  been  previously  considered  in 
its  special  application  to  porcelain  work  in  this  chapter.  The  various 
steps  in  this  style  of  construction  are  illustrated  in  Fig.  194. 

The  Logan  crown  may  be  used  in  similar  man- 
Hpplication  of         ncr,  with  either  a  band  or  simple  plate,  and  the  differ- 
tbC  COflan  Grown.       encc  in  the  procedure  incident  to  its  employment  lies 
in  the  absence  of  any  necessity  for  using  other  than 
the  original  dowel,  which  is  of  platinum  and  which  constitutes  an  insepar- 
able part  of  the  crown. 

The  presence  of  an  inseparable  dowel  in  this  connection,  however, 
adds  somewhat  to  the  detail  involved  in  grinding  the  crown  to  the  required 
adaptation  with  the  cap  or  plate,  and  necessitates  subjecting  the  porcelain 


254 

lo  the  heat  of  soldering  in  attaching  it  thereto,  which,  of  course,  is  not  true 
in  the  use  of  the  Davis  crown. 

In  the  apphcation  of  this  crown  in  combination 
ProcedUK.  with  porcelain  and  a  platinum  cap  or  plate,  the  same 

detail  as  indicated  in  connection  with  the  use  of  gold 
should  be  observed. 


5y^  195, 


The  base  should  be  constructed  of  platinum  of  the  same  gauge  as 
for  the  Davis  crown,  and  the  temporary  dowel  should  be  adjusted,  the 
impression  taken,  and  the  model  secured  in  accordance  with  the  detail 
previously  outlined  in  the  consideration  of  this  style  of  crown  in  com- 
bination with  gold. 


/9y.  196. 


The  crown  should  be  then  selected,  ground  as  thus  indicated  (Fig. 
195,  A),  attached  to  the  base  with  a  minute  quantity  of  adhesive  wax, 
removed  from  the  model,  invested,  and  the  relation  between  the  base  and 
dowel  permanently  sustained  with  a  small  quantity  of  pure  gold,  to  pre- 
clude any  possible  change  which  might  result  from  the  shrinkage  of 
porcelain. 


255 

The  soldering  may  be  done  with  greater  facility  by  covering  the  entirt 
crown  with  investment  material,  leaving  only  the  surface  of  the  base, 
which  comes  in  contact  with  the  root  and  the  dowel,  exposed.  (Fig.  196.) 
Considerable  care  must  be  exercised  in  this  procedure,  however,  to  prevent 
fracturing  the  porcelain,  which  can  only  be  avoided  by  thoroughly  heating 
the  latter  before  attempting  to  solder.  This  space  between  base  and  crown 
may  then  be  filled  with  porcelain  "body"  and  fused,  and  the  finished  crown 
is  illustrated  in  Fig    195,  B. 

Use  of  "Plastic"  or  **mouWaWc"  Porcelain  In  effecting  JIdaptatlon. 

\'arious  forms  of  extremely  low  fusing  compounds  of  porcelain  and 
other  basal  ingredients  combined,  and  known  as  "Plastic"  or  "jMould- 
able"  porcelain,  are  being  recommended  and  used  to  some  extent  in  effect- 
ing a  more  accurate  adaptation  of  any  of  the  various  forms  of  ready- 
made  porcelain  crowns,  than  could  be  obtained  by  grinding. 

In  the  use  of  such  compounds  they  are  mixed  to  a  thick  putty-like 
consistency,  and  after  the  crown  has  been  ground  to  an  approximate 
adjustment,  this  is  then  placed  over  the  base  and  forced  to  position  on 
the  root,  thus  moulding  it  to  the  outline  of  both  the  base  and  periphery 
of  the  latter.  The  surplus  is  then  trimmed  away  flush  and  even,  and  the 
crown  placed  in  the  furnace  and  baked,  the  result  being  a  very  accurately 
adapted  crown. 

A  ver}-  ingenious  method  of  obtaining  accuracy 

lOhttStonc'S  ^'^  ^  somewhat  similar  manner  has  been  devised  by 

method.  Dr.    A.    P.    Johnstone.      In    this    process    the    ad- 

justment is  affected  by  first  moulding  zcax  to  the 
base  of  the  crown  and  end  of  the  root,  in  the  manner  just  previously 
indicated,  and  then  investing  the  crown  in  an  instrument  designed  for 
the  purpose,  and  which,  together  with  little  low  fusing  buttons  of  por- 
celain, affords  opportunity  for  accurately  and  automatical!}-  reproducing 
the  wax  base  with  porcelain.  This  very  useful  devise  is  manufactured  by 
the  Brewster  Dental  Co.,  of  Chicago. 

Either  of  these  procedures  is  an  improvement  upon  the  former 
method  of  grinding  the  adjustment,  and  affords  a  far  greater  degree  of 
accuracv. 


eompositiott,  Cbardcteristics  and  nidiiit^uldtion 
of  Porcelain  Boaiei 


CHAPTER  XIII. 

Porcelain  Compounds :  Composition ;  Silica,  Feldspar,  Kaolin,  "Flux,"  Col- 
oring Matter.  "High  and  Low"  Fusing  "Bodies" :  Comparative  Advantages. 
Shrinkage,  Fusing  Points.  "Gum  Enamel"  "Bodies."  Requirements  for 
Crown  and  Bridgework.  Manipulation  of  Body:  Preparation  of  Crown,  Se- 
lection of  Color,  Mixing  "Body,"  Applying  and  Building.  One  Grade  of 
"Body."  Variations  in  Shading;  Use  of  Oil  Colors;  Contouring  and  Carving. 
Primary  "Bake."  Final  "Bake."  "Foundation"  and  "Enamel"  "Bodies." 
Precautions  Incident  to  Fusing.  Supporting  Crown  in  Furnace.  Placing  Crown 
in  Furnace.  Heating  Furnace.  Fusing:  Tests,  Porosity.  Furnaces:  Electric 
Furnaces,  Gasoline  Furnaces,  Gas  Furnaces. 


Porcelain  Compounds. 

With  the  rapid  development  of  this  class  of  work,  a  demand  has 
been  created  for  the  production  of  porcelain  compounds  which  possess 
qualities  better  suited  to  the. requirements  of  manipulation  and  color  than 
was  characteristic  of  those  which  were  formerly  used,  and  which  had 
been  especially  prepared  for  continuous  gum  work. 

This  latter  grade  of  material,  as  originally  compounded  by  Dr.  John 
Allen,  and  later  by  Dr.  S.  L.  Close,  in  the  absence  of  anything  better, 
was  quite  commonly  used,  and,  when  more  finely  pulverized  to  admit 
of  being  carved  and  fused  with  greater  accuracy,  it  served  the  pur- 
pose so  well  as  to  be,  to  a  great  extent,  responsible  for  the  growth  and 
development  of  this  class  of  work  to  the  degree  of  its  present  successful 
attainment. 

As  it  was  prepared  in  only  one  grade  and  color,  however,  the  de- 


257 

mands  created  by  the  possibilities  of  this  work  soon  induced  other  man- 
ufacturers to  so  alter  and  improve  upon  these  materials  as  to  furnish 
compounds  which  would  be  somewhat  less  refractory,  and  which  would 
more  nearly  meet  the  requirements,  with  the  result  that  several  products 
are  now  prepared  in  different  grades  and  varying  colors. 

These  various  compounds  are  supplied  in  powder 
Composition.  form,  and  are  known  as  "bodies,"    "enamels,"    and 

"gum  enamels."  They  are  composed  of  silica,  feld- 
spar, kaolin  and  a  suitable  "flux,"  and  are  colored,  or  tinted,  with  metals 
or  metallic  oxides. 

Silica  is  the  dioxide  of  silicon,  a  very  refractory 
Silica.  and  practically  infusible  substance  found  in  the  form 

of  agate  and  flint.  It  is  the  base  of  all  true  porce- 
lain "bodies,"  and  imparts  structural  strength  to  them. 

Feldspar  is  a  double  silicate  of  aluminum  and 
feldspar.  potassium.     This   material  is  somewhat  less  refrac- 

tory than  silica,  and  is  incorporated  for  the  purpose 
of  imparting  stability  to,  and  increasing  the  translucency  of,  the  com- 
pound. 

Kaolin  is   the   hydrated   silicate    of    aluminum. 
Haolin.  This  is  a  very  fine  grade  of  clay,  and  is  a  most  essen- 

tial ingredient,  being  incorporated  for  the  purpose 
of  imparting  stability  of  form  by  holding  the  particles  together,  and  thus 
facilitating  the  moulding  and  carving  of  the  mass  into  the  desired  shape. 

The  "flux"  is  usually  composed  of  the  carbon- 
"TIUX."  ates  of  the  alkaline  metals,   sodium  and  potassium, 

though  in  some  classes  of  compounds  the  oxide  of 
lead  is  also  much  used. 

The  quantity  and  nature  of  the  "flux,"  and  the  manner  of  its  incor- 
poration determines  the  fusibility  of  the  former  refractory  ingredients, 
and  the  tensile  strength,  or  resistance  to  fracture,  of  the  mass  when  all 
are  fused  together. 

The  coloring  matter  employed  for  the  purpose 

Colorins  matter.       of  imparting  the  required  variations  of  shade  must 

necessarily  be  more  or  less  high  fusing  in  character, 

in  order  that  the  color,  or  tint,  may  not  be  dissipated,  or  burned  out.  in 

the  fusion  of  the  compound. 

While  the  coloring  matter  itself  has  practically  no  influence  upon  the 
fusibility  of  the  compound,  the  color  imparted  is,  however,  materially 
affected  by  the  degree  of  heat  required.  For  this  reason,  metals,  or  me- 
tallic oxides,  are  used  for  this  purpose,  in  which  the  basal  shades  im- 
parted are,  approximately,  as  follows : 


2SS 

Yellow,  ^.  Titanium. 

Brown,  Iron. 

Blue,  Cobalt. 

Gray,  Platinum. 

Pink    (gum   enamel),  Silver  and   tin   in   combination  with  gold 

(purple  of  cassius). 
The  colors  and  tints  characteristic  of  the  different  "bodies"  are  pro- 
duced by  the  use  of  these  in  various  compounds,  of  equally  varying  pro- 
portions, but  the  exact  formula  and  methods  of  procedure  are  of  special 
interest  to  the  manufacturers  only,  and  are  usually  more  or  less  care- 
fully guarded  by  them. 

"I)l9b"  and  **Cow"  fusing  "  Bodies." 

The  several  varieties  of  "body"  now  prepared  may  be  classified  into 
two  distinct  grades — the  so-called  "high"  and  "low"  fusing,  with  the  line 
of  common  distinction  between  them  being  based,  approximately,  upon 
the  fusing  point  of  pure  gold. 

An  intelligent  analysis  of  the  comparative  quali- 

SomparatiVC  ties  and  advantages  of  the  two  classes  of  "body" 

7ldt)ant(t9C$.  demands  a  more  or  less  limited  familiarity  with  the 

composition    of    these    compounds,     and     with     the 
characteristics  of  their  respective  ingredients. 

Silica  being  the  most  refractory  and  infusible  substance,  it  might  be 
commonly  supposed  that  a  "body"  capable  of  being  fused  at  a  lower 
temperature  than  another  would  necessarily  contain  less  of  this  ingre- 
dient and  more  feldspar  and  kaolin  in  proportion. 

Such  an  assumption  would  be  correct  if  the  "flux"  played  a  less  con- 
spicuous part  in  the  reduction,  but  the  same  relative  formula  of  the  three 
basal  ingredients  may  be  used,  and  yet  the  fusing  point  of  the  resulting 
compound  be  regulated  by  the  proportion  of  "flux"  subsequently  added 
to  this  formula. 

But  as  a  "body"  must  possess  sufficient  inherent  strength,  integrity 
and  stability  to  offer  a  high  degree  of  resistance  to  fracture,  and  must 
possess  translucency,  and  absence  of  opaqueness,  an  adequate  proportion 
of  these  three  basal  ingredients  seems  essentially  necessary,  since  each 
has  its  place  and  purposes  in  the  compound,  as  previously  indicated. 

This  being  apparent,  if  the  fusing  point  is  then  regulated  or  con- 
trolled by  the  proportion  of  "flux,"  and  it  is  conceded  that  the  latter  does 
not  impart  to  the  compound  the  highest  degree  of  strength  possible,  in 
the  light  of  our  present  knowledge  it  seems  reasonable  to  deduce  that, 
when  a  sufficient  pro])orlion  of  "flux"  to  reduce  the  fusing  point  of  these 
refractory  materials  below  a  certain  point  is  incorporated,  the  maximum 
degree  of  strength  possible  is  not  imparted  to,  nor  o]-)tained  in,  the  product. 


259 

It,  therefore,  seems  evident  that  when  a  maximum  des^ree  of 
strength  is  to  be  obtained,  such  as  is  required  in  the  construction  of 
crowns,  or  bridges,  where  at  best  the  friable  material  is  to  assume  the 
lull  stress  of  mastication,  by  direct  contact,  the  compound  which  will  best 
serve  the  purpose  must  be  one  possessing  the  integrity  and  stability  im- 
parted by  the  three  basal  ingredients  to  a  degree  not  entirely  destroyed 
by  the  incorporation  of  too  great  a  proportion  of  "flux." 

All    porcelain    compounds    shrink    in    fusing   in 
Shrinkage.  proportion   to   the   degree   of  their  fineness   of   tex- 

ture, and  the  quantity  and  nature  of  the  "flux"  used  ; 
and  the  degree  of  shrinkage  adds  to  the  difficulties  incident  to  their  man- 
ipulation with  certainty,  accuracy  and  expediency. 

The  "high"  fusing  compounds  shrink  from  ten  to  fifteen  per  cent, 
while  the  "low"  fusing  range  from  the  latter  point  up  to  25  per  cent, 
cind  some  of  the  glass  or  extremely  low  fusing  "bodies"  which  contain 
lead  in  large  proportions  even  greatly  exceed  this.  There  is  never  any 
indication  for  the  use  of  the  latter,  however,  because  of  their  minimum 
strength,  and  of  their  invariable  tendency  to  discolor  in  the  mouth,  which 
may  be  attributed  to  the  presence  of  the  lead. 

All  of  the  compounds  are  more  or  less  porous,  and  hence  trans- 
lucent, in  proportion  to  the  degree  of  fineness  to  which  they  are  pulver- 
ized before  fusing.  Hence,  as  the  lower  fusing  "bodies"  are  always  re- 
duced to  a  much  finer  texture  in  their  preparation,  they  possess  a  greater 
density  of  structure. 

This  increased  density,  however,  is  due  to  the  more  homogeneous 
coalescence  of  the  particles  as  a  result  of  the  more  thorough  admixture 
of  the  "flux,"  and  is  gained  at  the  expense  of  translucency  and  stability, 
since  the  "flux,"  beyond  a  certain  proportion,  does  not  add  integrity  to  the 
mass,  but,  on  the  contrary,  increases  the  shrinkage,  friability  and  tendency 
to  globulate  in  fusing. 

The  degree  of  shrinkage  is  a  very  objectionable  feature  in  this  work, 
where  so  large  a  quantity  of  body  is  used,  because  the  resistance  to  the 
contraction  which  takes  place  in  the  lower  fusing  "bodies,"  and  w-hich 
resistance  is  offered  by  contact  with  facing  and  cap,  induces  a  tendency 
to  fracture  which  greatly  diminishes  the  strength. 

A  summary  of  the  apparent  disadvantages  to  be  found  in  the  "low"" 
fusing  "bodies"  thus  consists  in  their  degree  of  contraction;  their  dimin- 
ished strength  and  translucency,  and  their  /(7c7o  of  stability  of  form  and 
color. 

These  features  also  make  their  manipulation  with  accuracy  and  cer- 
tainty more  difficult,  particularly  for  the  inexperienced,  because  of  the 
necessity   for  slnitting  ofif  the   heat   at  the  precise  degree  at   wliich  the 


26o 

proper  fusing  point  is  reached,  in  order  to  avoid  a  dissipation  of  the 
color,  and  a  loss  of  the  desired  form,  as  a  result  of  their  great  tendency 
to  become  spherical  immediately  following  the  definite  and  exact  point 
of  fusion. 

For  these  various  reasons,  the  use  of  the  "low"  fusing,  or  so-called 
"enamel  bodies,"  or  those  which  contain  a  large  enough  proportion  of 
"flux"  to  reduce  their  fusing  point  below  that  of  pure  gold,  and  to  de- 
crease the  stability  of  form  and  color,  which  are  imparted  largely  by  the 
three  basal  ingredients,  cannot  be  considered  at  the  present  time,  as  be- 
ing conservatively  reliable  for  this  special  class  of  work. 

Furthermore,  a  series  of  comparative  tests  for  crushing  and  tensile 
strength  of  most  of  the  various  "bodies''  now  prepared,  as  conducted  by 
Dr.  J.  E.  Nyman,  seems  to  prove  conclusively  that  the  most  useful  and 
reliable  compounds  for  this  class  of  work  are  to  be  found  among  those 
which  fuse  between  2,100°  and  2,500°  Fahrenheit,  with  the  pyrometer 
gauged  by  the  fusing  point  of  pure  gold,  as  being  2,016°. 

The  following  table  gives  the  approximate  fus- 

Tusing  Points.         ing  points  of  most  of  the  various  bodies  now  in  com- 
mon use,  as  well  as  of  the  different  makes  of  teeth, 
as  compiled  by  Mr.  J.  F.  Hammond,  and  Dr.  W.  A.  Capon,  in  the  Ham- 
mond Electric  Furnace : 


"Body."  Current. 

Jenkins's no  volts. 

Ash's   Low   Fusing no  " 

Ash's  High   Fusing no  " 

Mofifitt's    Porcelain 120  " 

Brewster's  Enamel no  " 

Consolidated's  High  Fusing,  no  " 

Whiteley's   Porcelain no  " 

Brewster's  Found  Body....  no  " 

Close's  Found   Body no  " 

White's    Porcelain no  " 

Parker's  Body 120  " 

Ash  and  Sons'  Tooth  Body,  no  " 

Sibley's   Tooth   Body no  " 

Dental     Protective's     Tooth 

Body    no  " 

Justi's  Tooth  Body no  volts. 

S.   S.   White's  Tooth   Body,  no  " 
Johnson    and    Lund's  Tooth 

Body    120  " 

Luken's  Tooth   Body 120  " 

Century  Tooth  Body 120  " 

Consoiidated  Mfg.  Co.'s  Tooth 

Body    120  " 


Rheostat. 

T 

ime. 

Tern.  Fahr. 

1st    Step. 

2  : 

min. 

1,544 

1st      " 

2 

** 

1,544 

4th     " 

2 

1,904 

2d        " 

2 

(( 

2,047 

4th     " 

2 

(( 

2,084 

5th     " 

2 

t( 

2,192 

5th     " 

2 

2,210 

5tli     " 

2 

u 

2,300 

5th     " 

2 

u 

2,300 

5tli     " 

2 

u 

2,300 

5th     " 

2 

it 

2,586 

4th     " 

2 

a 

2,264 

4th     " 

2 

(I 

2,408 

5th     " 

2 

li 

2,440 

5th  step. 

2  : 

mm. 

2,440 

6th     " 

2 

a 

2,516 

5th     " 

2 

li 

2,586 

5th     " 

0 

li 

2,606 

5th     " 

2 

(t 

2,624 

5th 


2,624 


26l 

•*6um  Gnamcr'  "Boaies," 

The  compounds  designated  as  "gum  enamel"  bodies  contain  a  larger 
proportion  of  "flux"  than  basal  bodies,  and  consequently  fuse  at  a  lower 
degree  of  heat,  and  possess  less  strength.  Hence,  when  their  use  is  in- 
dicated for  the  purpose  of  producing  an  artificial  restoration  of  the  gum 
color,  the  major  portion  of  the  contour  of  the  piece  should  be  made  of 
the  basal  "body,"  and  the  "gum  enamel"  subsequently  applied  where 
necessary,  and  only  for  the  purpose  of  imparting  the  gum  color. 

Previous  to  the  application  of  the  "gum  enamel,"  the  basal  "body" 
to  be  covered  by  it  should  be  fused  until  it  presents  a  fairly  smooth  and 
well-vitrified  surface.  This  is  necessary,  because  it  is  not  to  be  re-fused, 
and  the  maximum  degree  of  strength  will  not  obtain  until  its  particles 
are  well  coalesced,  and  all  shrinkage  has  taken  place,  and  if  this  is  ac- 
complished at  the  time  of  the  fusion  of  the  "gum  enamel,"  the  color  of 
the  latter  will  likely  be  burned  out  or  dissipated,  owing  to  its  greater 
fusibility,  and  its  surface  will  present  innumerable  fractures,  as  a  result 
of  the  further  shrinkage  of  the  base. 

A  new  form  of  "gum  enamel"  has  been  introduced  by  Mr.  Robert 
Brewster,  of  Chicago.  This  consists  of  a  finely  pulverized  "body,"  which 
is  mixed  to  the  desired  consistency  with  oil,  and  then  painted  upon  the 
surface  and  fused,  in  the  manner  previously  indicated,  in  connection  with 
the  use  of  "oil  colors." 

It  would  seem  that  this  should  prove  to  be  the  ideal  method,  because 
the  same  effect,  and  greater  variations  in  shading,  may  be  obtained,  with- 
out diminishing  the  strength  or  increasing  the  weight  or  bulk  of  the 
finished  piece. 

Kcquiremcnt$  for  Crown  and  BridgeworK. 

A  class  of  "body"  possessing  qualities  adaptable  to  the  maximum  re- 
quirements for  crown  and  bridgework  will  thus  doubtless  belong  to  the 
high  fusing  variety,  and  should  be  prepared  in  o}ie  grade;  of  a  sufficient 
variety  of  colors,  and  pulverized  only  to  a  degree  of  fineness  which  will 
admit  of  being  nicely  carved.  This  latter  feature  is  essential,  because 
the  shrinkage  is  increased  and  the  fusing  point  decreased  in  any  given 
compound  in  proportion  to  the  degree  of  fineness  in  which  it  is  prepared. 

Those  which  are  to  be  especially  recommended  are  Brewster's 
"Crozvn  and  Bridge/'  "S.  S.  White's;"  the  Consolidated  Dental  Mfg. 
Co.'s  and  Whiteley's  products,  all  of  which  are  supplied  in  neat  and 
compact  form,  in  a  good  variety  of  colors,  quite  adequate  to  the  require- 
ments for  this  work.  While  good  results  may  also  be  obtained  from  the 
use  of  Brewster's  "Inlav  Bodies,"  which  consist  of  tzvo  grades — "foun- 


262 

dation"  and  "enamel" — the  best  possible  results  are  doubtless  facilitated 
and  afforded  by  the  employment  of  one  grade  of  material  throughout  the 
construction  of  the  piece,  and  no  difficulty  will  be  encountered  in  obtain- 
ing the  deisred  enamel  surface  in  any  of  these  compounds,  if  they  are 
fused  to  the  proper  degree  of  vitrification,  without  the  use  of  any  of  the 
lower  fusing,  or  so-called  "enamel  bodies"  in  conjunction  therewith. 

mdnipuldtioit  of  ''Bodv/' 

That  portion  of  the  procedure  which  involves  the  manipulation  of 
the  "body"  requires  the  most  consummate  judgment  and  skill,  and,  while 
it  is  largely  true  that  the  strength  of  the  finished  piece  is  much  dependent 
upon  the  metal  constniction  which  forms  the  foundation  for  the  porce- 
lain, the  degree  of  possible  strength  may  be  still  further  increased  by  skil- 
ful manipulation  of  the  latter,  or,  as  the  converse  is  equally  true,  it  may 
be  diminished  accordingly. 

When  the  crown  has  been  taken  from  the 
Preparation  Of  €rowtl.  investment,  after  soldering,  it  should  first  be  thor- 
oughly cleaned  in  50  per  cent  sulphuric  acid,  in  or- 
der to  insure  the  removal  of  all  remaining  traces  of  borax  or  investment 
material  which  may  cling  to  it,  and  which  would  be  apt  to  interfere  with 
the  subsequent  fusion  of  the  porcelain ;  and  the  presence  of  borax  is  par- 
ticularly objectionable,  because  it  acts  as  a  "flux." 

The  surplus  ends  of  the  dowel  and  pins  should  be  ground  down 
smooth,  and  so  that  they  offer  no  obstruction  to  the  contour,  and  afford 
no  weakening  of  the  porcelain,  by  extending  or  projecting  into  it,  thus 
dividing  it  through  the  center,  and  all  sharp  angles  should  be  nicely 
rounded. 

These  requirements  are  imperative,  as  the  "body"  should  occupy  all 
of  the  space  possible.  It  will  not  fuse  down  close  nor  become  attached  to 
unclean  or  irregular  surfaces,  and  in  fusing  will  usually  either  draw  away 
from,  or  fracture  over,  sharp  angles  as  a  result  of  the  shrinkage. 

When  these  precautions  have  been  observed,  the  crown  should  be 
again  treated  to  the  acid  bath,  and  then  washed  freely  with  clean  water; 
if  a  carborundum  stone  has  been  used,  care  should  be  exercised  to 
remove  all  particles  which  may  cling  to,  or  remain  upon,  the  metal,  or 
facing,  as  the  presence  of  such  particles  will  invariably  cause  a  discolo- 
ration of  the  porcelain. 

A  close  observation  of  these  prerequisites,  combined  with  scrupulous 
care  and  extreme  cleanliness  throughout  the  subsequent  procedure,  wil) 
materially  increase  the  chances  of  securing  successful  results. 

These  results  will  also  be  greatly  facilitated  by  confining  the  work 


263 

to  a  place  especially  prepared  for  such  purposes,  or  to  a  portion  of  the 
work-bench  which  has  been  previously  cleaned  and  arranged ;  all  of 
the  necessary  instruments  and  appurtenances  to  be  used  should  likewise 
be  kept  perfectly  clean. 

When  a  suitable  place  to  work  is  thus  prepared, 
Selection  of  Color,      and  the  crown  is  ready  for  the  application    of    the 
■''body,"  its  dowel  should  be  grasped  firmly  between 
the  jaws  of  a  slide  pin-vise,  which  will  hold  it  securely  during  the  build- 
ing and  carving  (Fig.  197),  and  the  proper  color  of  "body"  then  selected. 
This  should  approach  the  shade  of  the  facing  when  one  is  used,  or 
else  of  the  color  desired,  as  closely  as  possible,  and  may  be  accomplished 
with  the  use  of  the  shade-guide,  which  accompanies  the  various  makes 
of  porcelain. 

If  the  exact  color  cannot  be  matched,  and  some  variation  becomes 
necessary,  a  shade  slightly  darker  than  the  facing  should  be  selected, 
owing  to  the  tendency  to  bleach  somewhat  in  fusing.  In  this  connection, 
it  must  be  remembered  that  the  true  color  of  the  porcelain  compound  will 
be  obtained  only  when  it  is  fused  to  the  exact  point  of  complete  vitrifica- 


Fig.  197. 

tion,  and  that  it  will  become  lighter  in  shade  as  it  is  carried  beyond,  or 
above,  this  point. 

An  adequate  quantity  of  the  "body,"  which  cor- 
niixins  "Body."  responds  in  color  to  that  selected  on  the  shade-guide, 
should  now  be  placed  upon  a  clean  porcelain  or  glass 
mixing  slab,  distilled  zvaicr  added,  and  then  mixed  thoroughly  with  a 
suitable  spatula,  until  it  assumes  the  consistency  of  thick  cream.  The 
water  may  be  added  in  the  most  convenient  and  expeditious  manner,  by 
means  of  the  "dropper,"  or  "pipette  bottle,"  such  as  is  contained  in  many 
outfits  for  this  work  and  which  also  serve  to  keep  it  pure  and  clean  for 
subsequent  use. 

Sufficient  water  to  insure  the  desired  coiisistency  and  thorough  mix- 
ing are  quite  essential,  and  any  surplus  of  "body"  is  not  wasted,  be- 
cause it  may  be  replaced  in  its  proper  receptacle  and  used  at  an- 
other time. 

Alcohol  is  sometimes  recommended  and  used  because  of  expediting 
the  evaporation  of  the  moisture  from  the  compound,  and  thus  facilitating 


264 

the  carving  of  the  mass,  but  this  feature,  because  of  usually  being  too 
rapid,  is  more  often  an  objection  than  an  advantage. 

The  addition  of  a  small  proportion  of  gum  tragacanth  to  the  water  is 
also  recommended  as  furnishing  a  means  of  adding  to  the  cohesion  of  the 
mass  after  the  evaporation  of  the  moisture,  and  thus  facilitating  the  carv- 
ing and  contouring,  but  its  presence  is  objectionable,  because  it  seemingly 
acts  as  a  "flux"  in  the  fusion  of  the  porcelain,  and  is  unnecessary,  because 
the  manufacturers  usually  incorporate  a  small  proportion  of  starch  in  the 
compound  for  this  special  purpose. 

The  use  of  pure  clean  water  is  preferable.  It  should  be  distilled, 
however,  because  the  presence  of  lime  or  organic  matter  may  have  an  in= 
jurious  effect  upon  the  fusion  of  the  porcelain. 

Jlpplyind  and  Buiiaing. 

In  the  manipulation  of  these  compounds,  it  must  be  remembered  that 
their  tendency  to  shrink  in  fusing  plays  quite  an  important  part,  and  gov- 
erns the  method  of  procedure  to  a  large  extent. 

In  the  use  of  one  grade  of  body,  having  the 
"One  6radC"  same  fusing  point,  throughout  the  construction  of 
Of  *"Body."  the  piece,  the  desired  shape  and  contour  for  the  fin- 

ished crown  should  obtain  for  the  first,  or  primary 

F/q.  198. 

"bake,"  and  yet  it  is  seldom  possible  and  never  expedient  to  complete  it 
in  one  "bake,"  because  of  the  shrinkage. 

This  latter  feature  necessitates  tzvo,  and  sometimes  even  more, 
"bakes,"  though  the  procedure  is  somewhat  facilitated  by  forming  the  de- 
sired contour,  even  to  the  requirements  of  occlusion  for  the  primary 
"bake,"  and  the  second  or  final  application  of  "body"  should  then  be  made 
for  the  express  purpose  of  restoring  that  portion  of  the  original  form 
which  has  been  somezvhat  changed  by  the  shrinkage  incident  to  the  pri- 
mary fusion  or  "bake." 

With  the  crown  grasped  firmly  in  the  ]Mn-vise  (Fig.  197),  and  thf' 
body  mixed  to  the  pro]XT  consistency,  a  small  quantity  should  be  picked 
up  with  the  point  of  a  suitable  instrument  and  first  forced  into  the  joint 
between  cap  and  facing. 

This  may  be  facilitated  by  gently  tai)ping  the  handle  of  the  pin-vise, 
or  by  drawing  a  coarsely  serrated  instrument  across  it,  and  the  procedure 
should  be  continued  until  the  "body"  is  thoroughly  packed  into  the  space 


265 

A  suitable  instrument,  designed  by  the  author,  for  universal  use  in 
this  work,  and  combining  a  spatula  for  mixing,  a  serrated  shank  for 
packing,  and  a  pointed  blade  for  carving,  is  illustrated  in  Fig.  19S. 

This  feature  of  packing  is  imperative  throughout  the  entire  building 
up  of  the  crown,  as  a  means  of  insuring  a  high  degree  of  integrity  in  the 
mass  when  fused,  and  of  overcoming  the  tendency  toward  porosity  in 
fusing,  by  insuring  a  close  and  compact  coalescence  of  the  particles. 

As  the  building  up  progresses  and  each  additional  application  of 
body  is  thus  carried  to  place,  and  the  contour  formed,  the  procedure  may 
be  facilitated  by  absorbing  the  excess  moisture,  as  it  is  brought  to  the 
surface,  with  a  clean  piece  of  linen  or  cotton  cloth,  or  blotting  or  bibulous 
paper,  until  the  approximate  outline  for  the  finished  crown,  zvith  a  slight 
surplus,  obtains. 

The  latter  part  of  the  procedure  may  be  accomplished  with  greater 
ease  and  facility  by  mixing  the  body  to  a  thicker  consistency  after  the 
joints  and  all  small  interstices  are  well  filled. 

When  the  required  form  has  been  obtained,  the  remaining  moisture 
may  be  then  more  quickly  evaporated  by  passing  the  crozvn  over  a  flame 
until  the  mass  is  sufficiently  dry  to  admit  of  being  nicely  carved. 

The  "body"  should  always  remain  moist  enough,  however,  to  be 
carved  and  trimmed  without  flaking  or  crumbling,  and  in  the  event  of 
its  becoming  too  dry  to  admit  of  this,  it  may  be  again  slightly  moistened 
by  touching  it  with  a  wet  brush. 

In  building  up  bicuspids  and  molars,  after  first  filling  the  joint,  a 
narrow  strip  of  blotting  paper  may  be  conformed  to  the  outline  of 
the  lingual  portion  of  the  band,  and  when  held  in  place  will  serve  as  a 
matrix  to  hold  the  body  in  shape  which  thus  facilitates  the  procedure. 

Variations  of  shade  may  be  quite  easily  obtained 
Uariations  in  SbaLing.  by  selecting  the  appropriate  colors  of  body  and  mix- 
ing them  separately.  The  color  indicated  for  the 
base  of  the  crown  should  then  be  applied,  and  built  up  to  the  desired 
point,  when  the  other  may  be  added  without  allowing  the  first  to  become 
completely  dry. 

Their  use  in  this  manner  affords  opportunity  for  blending  them  ir. 
fusing,  and  very  artistic  results  are  possible,  particularly  in  those  cases 
where  the  base  should  be  yellow,  or  brown,  and  the  incisal  or  occlusal 
end  blue,  or  gray,  in  any  of  their  variations. 

The  use  of  the  oil  colors  previously  mentioned 
Use  ©f  Oil  €0l#r$,       may   also   be  productive   of  most  excellent  and   ar- 
tistic results.     They  should  be  thoroughly  mixed  to 
a   thin   consistency,  with   the   accompanying  oil,  applied    with    a    small 
brush,  and  separately  fused. 


266 

Where  it  is  desirable  to  proauce  a  change  in  the  color  of  the  facing, 
these  colors  should  be  applied  at  the  desired  point  on  the  lingual  surface, 
and  then  fused,  after  which  the  "body"  may  be  applied,  as  required,  and 
the  underlying  color  will  show  through  the  more  or  less  transparent 
facing.    . 

An  appreciable  change  in  the  color  of  the  porcelain  forming  the  body 
of  the  crown  may  also  be  produced  by  applying  and  fusing  these  colors 
to  the  surface  after  the  primary  bake,  when  the  final  contouring  may  be 
made,  the  transparency  of  which,  after  fusion,  will  indicate  the  presence 
of  the  underlying  color. 

In  simulating  the  characteristics  of  remaining  natural  teeth,  grooves, 
pits  and  sulci  may  be  colored  or  tinted  as  desired.  As  these  colors  fuse 
lower  than  the  "body,"  however,  this  work  can  be  done  to  the  best  ad- 
vantage after  the  crozvn  has  been  otherzvise  completed;  and  when  they 
are  used  for  such  purposes  on  the  labial  or  buccal  surfaces  of  the  facings, 
the  desired  inequalities  should  first  be  ground  with  a  small  carborundum 
stone  in  the  engine,  and  this  outline  then  properly  colored  or  tinted,  and 
the  crown  again  fused  until  the  colors  become  vitreous. 

If  not  too  dry,   the  procedure  incident  to  con- 
€ontOUrins  touring  and  carving  the  "body"  is  quite  simple,  but 

and  CarviltS.         the  artistic  results  will  depend  much  upon  personal 
equation  and  knowledge  of  the  forms  of  teeth. 

This  may  be  easily  acquired  by  a  close  study  of  natural  teeth,  and 
a  good  plaster  model  of  a  full  typical  arch  will  assist  by  serving  as  a  guide 
in  the  execution  of  this  work. 

As  has  been  previously  stated,  anatomically  correct  outlines  are  not 
essentially  necessary,  and  artistic  results  may  be  obtained  by  simply  so 
typifying  the  cusps  as  to  distinguish  between  the  right  and  the  left,  the 
upper  and  the  lower  teeth. 

The  requirements  of  occlusion  with  the  opposing,  and  contact  with 
the  adjacent,  teeth  may  be  observed  by  trying  the  crown  upon  the  model 
during  the  process  of  carving,  and  in  order  to  prevent  flaking  the  body 
or  changing  its  given  form,  it  may  be  carefully  and  slightly  moistened 
with  a  wet  brush  previous  to  such  trials. 

For  this  reason,  it  is  always  necessary  to  have  a  good  model  to 
which  the  crown  may  be  easily  adjusted  to  position,  as  has  been  pre- 
viously recommended. 

In  contouring  and  trimming  the  porcelain,  it  must  not  overlap  the 
band,  upon  any  surface,  nor  at  any  point,  excepting  along  the  labial  or 
buccal  surface,  ivhere  the  facing  mechanically  retains  it,  for  without 
such  means  of  retention  it  will  invariably  fracture  or  break  away,  leaving 
a  rough,  sharp,  or  irregular  joint  with  the  cap;  and  previous  to  placing 


267 

the  crown  in  the  furnace  all  particles  of  body  which  remain  deposited 
upon,  or  overlapping,  the  surface  of  the  facing,  or  which  may  have  found 
lodgment  on  the  inside  of  the  cap,  or  on  the  under  surface  of  the  base, 
should  be  carefully  removed  with  a  clean,  dry  brush  to  prevent  it  from 
becoming  attached  in  fusing. 

The  brushes  used  in  this  work  should  be  of  a  good  quality,  such  as 
are  employed  in  water  color  painting,  and  the  three  useful  sizes  and 
shapes  are  illustrated  in  Fig.  199.  The  largest  size  should  always  be 
kept  dry  and  used  only  for  smoothing  up  the  work,  while  the  medium 


FlcjJ99, 


Fiq.200. 


size  should  be  employed  for  the  purpose  of  moistening  the  "body,"  when 
necessary,  and  the  smaller  one  only  for  painting,  or  deepening  the  finer 
lines  in  carving. 

A  very  convenient  form  of  simple  carving  instrument,  designed  by 
Mr.  Robert  Brewster,  is  illustrated  in  Fig.  200. 

In  trimming  the  body,  the  allowance  of  a  slight  surplus  is  demanded 
by  the  shrinkage,  but  the  exact  extetit  may  only  be  ascertained  with  ac- 
curacy by  a  familiarity  with  the  compound  used,  as  all  vary  considerably 
in  such  properties. 


268 

The  crown,  when  the  body  has  been  trimmed,  and  carved,  and  when 
ready  for  the  primary  "bake,"  is  illustrated  in  Fig.  201  A. 

When  this  desired  form,  and  blending  of  color, 

Primary  **BakC«**      have  been  obtained,  the  crown  should  be  placed  in 

the  furnace  and  "baked"  until    the    body    becomes 

slightly  vitrified,  and  the  particles  zvell  coalesced,  but  its  surface  should 

not  he  highly  glased  at  this  time. 

This  degre'e  of  fusion,  or  vitrification,  is  preferable  to  the  so-called 
biscuit  bake,  commonly  advocated,  because  of  the  desirability  of  securing 
a  maximum  degree  of  shrinkage  in  the  primary  fusion,  but  the  surface 
should  not  be  allowed  to  become  smooth  and  vitreous  at  this  time,  be- 
cause the  second  application  of  the  body  will  not  adhere  so  well  to  it. 
Fig.  201  B  illustrates  the  appearance  of  the  crown  after  the  "primary, 
bake,"  and  indicates  the  degree  of  shrinkage  and  consequent  change  of 
form  which  takes  place. 


For  the  final  "bake,"  the  crown  should  be  again 
Tinal  "Bake."  adjusted  in  the  pin-vise  and  the  "body"  thoroughly 
mixed,  to  a  thin  consistency,  and  first  zvorked  well 
down  into  every  crevice  and  fissure  caused  by  the  shrinkage,  and  then  ap- 
plied over  the  surface  until  the  desired  contour  has  been  obtained,  when  it 
should  be  fused  to  the  required  degree  of  vitrification  for  the  finished 
work,  which  is  illustrated  in  Fig.  201  C. 

If  the  crown  comes  out  of  the  furnace  after  this  "bake"  presenting 
an  irregular  or  broken  surface  of  porcelain,  such  places  should  be  filled 
with  "body,"  and  again  fused,  though  if  the  proper  precautions  are  ob- 
served, this  will  seldom  be  necessary. 

When  two  grades  of  "body"  which  fuse  at  dif- 

"Toundatlon"  and     ferent  temperatures,   such  as  the  so-called  "founda- 

**6nanier'  Bodies,     tion"  and  "enamel  bodies,"  are  used,  the  requirements 

are  somewhat  different  from  those  indicated  for  one 

grade  of  body,  because,  if  the  desired  contour  of  the  crown  is  obtaijied 

m  the  primary  formation  and  fusion,  it  will  be  difficult  to  manipulate  the 

"enamel"  body  for  the  final  bake,  as  it  will  necessarily  need  to  be  applied 

sc   thinly  over  the  surface  of  the  "foundation"  body  as  to  preclude  any 


269 

carving,  and  increase  the  tendency  to  flake  off,  or  become  detached  in 
places,  before  fusing. 

Hence,  where  it  is  desirable  to  use  two  grades,  the  higher  fusing,  or 
"foundation,"  body  should  be  applied  first,  only  in  quantity  sufficient  to 
indicate  the  desired  form,  as  illustrated  in  Fig.  202  A. 

This  should  be  fused  and  the  lower  fusing,  or  "enamel,"  body  then 
applied,  trimmed  and  carved  as  desired  (Fig.  202  B),  and  then  fused. 


b 

The  increased  quantity  of  the  latter  body  and  its  greater  shrinkage 
demands  an  allowance  of  more  surplus  than  would  be  necessary  if  the 
same  higher  fusing  body  were  used  throughout. 

Precautions  Tncident  to  Tusittd. 

No  portion  of  this  work  is  of  more  importance  than  the  "baking" 
or  fusing  of  the  body,  because  the  strength  of  the  porcelain,  and  its  true 
color,  no  matter  to  which  class  it  belongs,  are  entirely  dependent  upon  its 
being  properly  fused. 


Fi<j.203. 

When  the   crown   is   ready    for  the   furnace,   it 

Supporting  Crcwn      must  be  adjusted  to    a    suitable    form,    which    will 

inTurnacc.  accommodate  the  dozvel,  support    the    base    of    the 

crozvn  by  allowing  it  to  rest  firmly  a}id  evenly,  and 

which  will  sustain  it  in  a  perpendicular  position  while  in  the  furnace. 

Whilst  platinum  trays  were  first  used,  and  are  even  now  occasionally 
recommended,  for  this  purpose,  their  employment  is  objectionable  be- 
cause crowns  not  infrequently  become  attached  to  them  in  fusing,  and 


270 


in  the  subsequent  detachment  the  porcelain  may  be  checked,  or  the  shape 
of  the  band  altered. 

This  attachment  may  be  due  to  the  re-fusion  and  flowing  of  a  surplus 
of  the  pure  gold,  when  such  is  used  in  soldering,  or  to  an  excess,  or  the 
over-fusing,  of  the  porcelain,  but  whatever  the  cause,  may  be  precluded 
by  the  use  of  supports  made  of  fire-clay  or  chalk,  of  suitable  form. 

The  proper  adjustment  of  a  crown  with  and  without  a  band,  to  the 
style  of  support  indicated  for  each,  is  illustrated  in  Fig.  203. 

Such  supports  may  be  made  by  moulding  a  good  grade  of  fire-clay 
to  the  desired  shape,  and  "baking"  it ;  or  may  be  procured  in  various 
designs  to  meet  the  equally  varying  requirements  of  practically  inde- 
structible material  from  many  of  the  manufacturers  of  furnaces  and 
"bodies." 

Useful  designs  for  this  purpose  are  supplied  by  Dr.  R.  C.  Brophy, 
of  Chicago  (Fig.  204),  or  may  be  made  by  trimming  down  a  piece  of 
ordinary  blackboard  chalk  to  meet  the  requirements  of  the  case. 


m'i''^- -■>*-■* 

^(\4'|!v^ 

mi 

llpl 

K-'i'.'f.iB!: 

The  latter  is  composed  of  compounds  of  magnesium  and  calcium, 
which  are  practically  infusible,  and  being  very  inexpensive,  it  is  quite 
useful.  Such  supports  will  serve  the  purpose  nicely  for  individual  fus- 
ings  and  may  even  be  used  two  or  three  times  before  the  form  is  lost, 

In  placing  the  crown  in  the  furnace,  it  should 
be  observed  that  the  dowel  does  not  extend  entirely 
through  the  perforation  for  its  accommodation  in  the 
support,  so  as  to  bring  its  end  in  contact  with  the 
and  that  the  facing  does  not  touch  the  dome  or  sides 
of  the  latter,  as  such  contact  in  either  instance  will  invariably  result  in  a 
fracture  of  the  facing,  due  to  too  rapid  heating,  or  uneven  expansion. 

The  crown  should  be  held  in  a  perpendicular  position,  if  possible, 
in  order  to  prevent  any  change  of  form  which  might  be  induced 
by  tlie  influence  of  gravity,  when  the  mass  is  in  the  fused  state ;  and  the 
body  should  always  present  toward  the  opening  or  door  of  the  muffle,  so 
that  it  may  be  closely  watched  while  fusing.     This  latter  feature  is  of 


Placiitfl  Crown 
In  Turnacc. 

floor  of  the  muffle 


271 

special  importance,  because  if  the  body  is  not  visible  to  the  eye,  portions 
of  it  may  flake  off  unnoticed  during  the  heating  of  the  case,  and  neces- 
sitate a  subsequent  bake,  to  avoid  which  it  should  always  be  heated  care- 
fully and   watched   closely   during  the  fusing. 

As  a  matter  of  expediency,  the  heating  of  the 
1>C(ltin0  Turnacc.       furnace  should  begin  immediately  preceding,  or  dur- 
ing, the  building  up  of  the  crown,  so  that  the  muffle 
will  be  thoroughly,  but  not  excessively,  heated  when  the  crown  is  ready 
for  the  baking. 

When  these  precautions  have  been  observed,  the  support  carrying 
the  crown  should  be  placed  near  the  opening  of  the  heated  muffle  and 
allowed  to  remain  for  a  few  moments,  in  order  to  become  thoroughly 
dry  before  it  is  placed  inside  of  the  furnace.  This  will  preclude  blistering 
the  surface  of  the  "body,"  or  the  displacement,  or  flaking,  of  particles 
from  the  crown,  as  a  result  of  the  expansion  of  the  remaining  moisture, 
which  would  be  induced  by  too  rapid  heating. 

In  placing  the  crown  in  the  furnace,  it  should  be  carried  to  a  posi- 
tion as  nearly  in  the  center  of  the  muffle  as  possible,  or  to  that  point  where 
there  are  the  greatest  number  of  heat  units.  For  the  reason  that  this  heat 
area  varies  to  a  considerable  extent,  it  is  seldom  advisable  in  the  smaller 
crowu  furnaces,  with  the  opening  in  one  end  only,  to  fuse  more  than  one 
or  two  crowns  at  a  time,  and  if  each  is  to  be  baked  uniformly,  they  must 
be  placed  crosszuise  in  the  muffle,  in  order  to  get  such  a  result,  as  the 
temperature  decreases  toward  the  door  or  opening. 

Tuslng. 

In  the  fusing  of  porcelain  "bodies"  the  physical  process  involved 
constitutes  changing  the  powdered  granular  mass  into  a  vitreous  sub- 
stance, which  is  then  more  or  less  homogeneous  in  proportion  to  the 
thorough  admixture  of  the  "flux,"  or  the  degree  of  complete  coalescence 
of  all  of  the  particles. 

Hence  the  proper  fusing  of  these  compounds  is  largely  a  matter  of 
experience.  In  the  lower  fusing  "bodies"  the  proper  and  desired  degree 
of  vitrification  may  be  easily  and  definitely  ascertained  by  observing  this 
physical  change  as  it  is  produced  by  the  application  of  heat.  This  is  also 
true  of  the  higher  fusing  bodies,  but  the  greater  degree  of  heat  required, 
and  the  consequent  incandescence  within  the  furnace  makes  it  more  diffi- 
cult. The  eye  may  be  trained  to  a  degree  of  familiarity  with  the  physical 
changes,  however,  which  will  enable  the  experienced  operator  to  more 
or  less  easily  distinguish  the  disappearance  of  the  rough  or  granular  sur- 
face, and  the  appearance  of  the  smooth,  glassy  or  vitreous  surface  even 
in  the,  at  first,  somewhat  trying  glare  of  the  incandescent  heat,  without 


2/2 

greatly  endangering  or  impairing  the  sight,  because  it  is  not  necessary 
to  bring  the  eyes  close  enough  to  the  furnace  to  be  seriously  affected  by 
the  heat. 

Smoked  or  colored  glasses  may  be  found  useful  in  this  connection, 
and  during  the  fusing  of  the  "body"  the  furnace  may  be  occasionally 
opened  for  this  purpose  without  danger  of  fracturing  the  facing,  be- 
cause the  volume  of  heat  is  too  great  to  admit  of  the  ingress  of  cold  air. 
While  everyone  desiring  to  do  this  class  of  work  in  the  most  accurate 
and  successful  manner  should  cultivate  this  degree  of  familiarity  with  the 
characteristic  appearance  of  the  "body"  in  the  various  stages  of  vitrifica- 
tion, it  can  only  be  acquired  through  experience.  When  the  crown  is 
properly  placed  in  the  furnace  the  heat  should  be  gradually  increased 
until  a  bright  red  color  is  produced.  This  may  be  done  by  degrees  with- 
out observing  the  crown  itself,  but  from  this  point  on  the  latter  should  be 
watched  closely  so  as  to  observe  when  the  rough  and  granular  surface 
becomes  smooth  and  vitreous,  which  to  the  experienced  eye  is  indicated 
by  the  degree  of  incandescence,  and  as  soon  as  a  glassy  appearance  has 
spread  over  the  entire  surface  of  the  porcelain  the  heat  should  be  imme- 
diately turned  off. 

Many  tests   for  determining  the  exact  heat  re- 
tWt$.  quired   to   properly   fuse  the  various   "bodies"   have 

been  suggested.  Alloys  of  platinum  and  gold  pre- 
pared in  various  proportions  with  a  view  to  having  the  test  metal  melt  at 
the  same  point  as  the  porcelain  would  greatly  facilitate  the  fusing,  but  as 
this  requires  a  special  alloy  for  each  kind  of  "body,"  and  as  these  are  not 
on  sale  ready  prepared  at  the  present  time,  it  involves  considerable  experi- 
mentation to  apply  this  method. 

Pure   gold   may  be   used  with   some   degree  of 
Pure  Gold.  facility,  and  its   use   is  recommended  as  a  guide  to 

the  beginner  and  an  aid  even  to  the  experienced.  A 
pellet  of  foil,  or  a  globule  previously  flattened  on  the  anvil  for  each  fus- 
ing may  be  placed  alongside  of  the  crown  in  the  furnace.  When  this 
fuses,  which  may  be  noted  by  its  assu^iing  globular  form,  the  beginning 
of  vitrification  of  nearly  all  of  the  higher  fusing  bodies  will  be  indicated. 
From  the  moment  of  the  fusion  of  the  gold  to  the  required  or  de- 
sired point  of  vitrification  of  the  porcelain,  time  is  the  only  reliable  test 
other  than  the  eye,  and  as  this  varies  with  each  furnace  and  class  of  body, 
it  must  be  previously  more  or  less  definitely  ascertained  by  experimen- 
tation. 

The  separate  fusing  of  several  cubes  of  the  "body"  used  will  enable 
one  to  ascertain  the  exact  time  after  the  fusion  of  the  pure  gold  with 
approximate  exactness.     When  the  desired    point    of    fusion    has    been 


273 

reached  the  heat  should  be  immediately  shut  off,  and  the  crown  allowed 
to  cool  slowly  until  a  low  temperature  obtains,  when  it  may  be  removed 
from  the  furnace.  Whilst  immediate  removal  as  soon  as  the  heat  is 
turned  off,  and  then  placing-  the  crown  in  a  cooling  muffle,  or  in  some  con- 
venient receptacle  where  the  air  will  be  excluded  until  it  is  cold,  is  some- 
times recommended,  and  is  permissible  in  emergencies,  the  furnace  itself 
affords  the  best  "cooling  muffle,"  and  the  slow  and  gradual  cooling  of 
the  piece  seems  to  "temper"  or  anneal  the  body,  and  thus  render  it  less 
brittle. 

Porosity  of  the  body  after  fusing  is  one  of  the 
PoroMty.  chief  causes  of  failure  in  this  work.     When  this  oc- 

curs it  may  invariably  be  attributed  to  one  of  three 
causes, — the  use  of  a  surplus  of  pure  gold  in  soldering;  imperfectly 
"packing"  the  body  in  building  up  the  crown,  or  overfusing  it  in  the 
furnace. 


Fj<j,20ff, 


An  excess  of  pure  gold  which  occupies  space  and  which  space  sub- 
sequently becomes  a  vacuum  when  the  gold  is  fused  in  the  furnace  and 
absorbed  by  the  platinum,  can  be  avoided  by  using  a  minimum  quantity 
of,  and  properly  fusing  the  gold  during  the  process  of  soldering. 

There  is  no  excuse  for  imperfect  "packing"  if  the  precautions  indi- 
cated are  observed ;  and  "overfusing,"  which  will  be  denoted  by  the  be- 
ginning of  a  change  of  form,  will  not  occur  if  the  case  is  watched  closely 
while  in  the  furnace,  or  the  time  test  is  accurate.  This  is  extremely 
essential  to  the  success  of  the  finished  work,  because  overfusing  burns 
out,  or  dissipates,  the  color,  and  destroys  the  integrity  of  the  material,  no 
matter  to  which  class  it  belongs. 

When  the  final  baking  has  been  completed  the  exposed  Ungual  sur- 


274 

face  and  entire  edge  of  the  platinum  band  should  be  smoothed  with  sand- 
paper and  polished  with  cuttle-fish  disks,  and  the  crown  then  tried  to 
place  and  mounted. 

Turnaces. 

Several  varieties  of  furnaces  are  now  made  for  porcelain  work  in 
which  three  sources  of  heat  production  are  successfully  employed, — elec- 
tricity, gasoline  and  gas. 

The  electric  furnaces,  or  "ovens,"  in  which  the 

€kCtrlC  TurnacCS.      heat    is    obtained    by    the    passing    of    the    current 

through    a    close    coiling    of    small    platinum    wire 

slightly  imbedded  in  fire-clay  without  contact,  or  wound  around  the  out- 


Ficj.206> 

side  of  a  thin  muffle,  possess  the  advantages  of  purity,  range  and  control 
of  heat,  and  of  cleanliness  and  the  absence  of  noise  or  odor. 

Owing  to  the  absolute  purity  of  the  heat  thus  obtained  any  possible 
danger  of  discoloring  the  porcelain  from  "gassing,"  is  eliminated ;  and 
for  all  of  the  combined  reasons  mentioned  the  use  of  the  electric  furnace 
is  recommended  wherever  it  is  possible  to  secure  suitable  commercial 
current,  such  as  is  supplied  for  incandescent  purposes. 

Of  the  several  makes  of  these  furnaces  especially  constructed  for 
small  work,  such  as  single  crowns  and  small  bridges,  those  known  as  the 


^75 

"Hammond,"  "Cnster"  and  "Pelton"  are  to  be  recommended  as  bemg 
leat,  compact  and  serviceable,  as  are  also  the  "Roach"  automatic,  and 
the  "Price"  and  "Garhart"  Pyrometer  designs. 

These  furnaces  include  a  rheostat  in  serial  connection  with  the  muffle 
or  "oven"  and  forming  the  base  of  the  furnace,  and  they  work  equally 
well  on  either  the  direct  or  alternating  currents  of  the  same  voltage. 

While  the  two  former  furnaces  are  made  in  three  sizes,  the  Hammond 
No.  2,  Fig.  205,  and  the  Custer  No.  5,  Fig.  206,  will  be  found  to  be  the 
most  convenient  size  for  this  special  work,  though  there  i*^  no  objection  to 
using  the  larger  sizes  which  are  designed  for  continuous  gum.  work  when 
several  crowns  at  one  time,  or  large  bridges,  are  to  be  "baked." 

As  the  larger  sizes  require  more  time  in  fusing,  it  is  more  expedient 
to  use  the  smaller  ones  for  crown  work.  The  opening  in  the  latter, 
however,  is  in  one  end,  hence  the  heat  is  greatest  as  the  back  wall  of  the 
muffle  is  approached.  For  this  reason,  if  more  than  one  piece  is  "baked" 
at  the  same  time,  they  must  be  placed  crosswise  and  not  lengthzvise  with 
the  muffle,  in  order  that  the  porcelain  may  be  uniformly  fused. 


Fiq.207, 


When  the  piece  is  adjusted  in  the  heated  furnace  it  should  be 
allowed  to  remain  for  a  few  moments,  and  the  lever  controlling  the 
rheostat  then  gradually  and  consecutively  pushed  from  button  to  button, 
with  an  interval  of  from  one  to  two  minutes  between  each.  When  the 
last  or  highest  step  required  is  reached,  the  case  should  be  closely  watched 
until  the  body  is  properly  fused,  or  timed  from  the  fusing  of  the  pure 
gold,  when  the  lever  should  be  immediately  reversed,  and  the  piece 
allowed  to  cool  more  or  less  slowly  before  removing. 

Convenient  pliers  of  special  design,  suitable  for  inserting  or  remov- 
ing the  support  containing  the  piece,  are  illustrated  in  Fig.  207,  but, 
while  these  are  also  very  useful  for  solder  work  in  general,  because  of 
their  length,  a  special  pair,  kept  perfectly  clean,  should  be  used  for  this 
work.  In  using  pliers  in  the  furnace,  however,  when  the  current  is  turned 
on  care  must  be  exercised  to  avoid  bringing  them  in  contact  with  the 
wires,  and  thus  possibly  fusing  the  latter  or  "burning  out"  the  furnace 
by  short-circuiting. 


2/6 


Fiq.  208. 


Ficj,  209 


277 

Where  it  is  not  possible   to  secure  commercial 
Gasoline  TUfltaccs.     electric    current,    and    for    reasons  of  possible  emer- 
gency and  economy,  the  gasoline  and  gas  furnaces, 
as  now  made,  will  serve  the  purpose  nicely,  and  when  properly  used,  will 
furnish  adequate  heat. 

While  it  is  true  that  such  facilities  do  not  afford  the  same  degree 
of  absolute  purity  of  heat,  there  is  but  little  danger  of  "gassing"  or  dis- 
coloring the  porcelain,  in  their  use,  if  the  continuity  of  the  muffle  is  per- 
fect. 

The  gasoline  furnace  is  preferable  to  gas  because  the  heat  produc- 
tion is  aided  by  means  of  a  pneumatic  pump  and  the  one  manufactured 
by  Dr.  R.  C.  Brophy,  of  Chicago,  Fig.  208,  especially  designed  for  crown 


FJcj.2\0. 


and  bridgework,  is  adequate  to  the  requirements  in  every  respect.  This 
furnace  is  made  in  two  styles,  one  with  a  very  thin  fire-clay  muffle,  and 
the  other  with  a  nickel  muffle,  both  of  which  are  quite  serviceable,  with 
the  preference  perhaps  slightly  in  favor  of  the  former. 

The  Turner  gasoline  furnace.  Fig.  209,  manufactured  by  the  Turner 
Brass  Works,  of  Chicago,  is  similar  in  design  (except  that  the  nickel 
muffle  is  exclusively  used),  and  is  perhaps  equally  as  effective. 

In  the  use  of  these  furnaces  they  should  be  started  and  well  heated 
before  the  work  is  placed  in  the  muffle,  and  the  piece  should  first  be 
thoroughly  dried  and  heated  at  the  opening  before  being  carried  into  the 
inside. 

As  the  muffle  opens  from  one  end  the  same  precautions  indicated 
in  connection  with  ;  imilarly  constructed  electric  furnaces  should  be  ob- 


2/8 

served,  and  when  the  work  is  finally  adjusted  to  place,  the  opening  should 
be  closed  as  a  means  of  confining  the  heat  to  the  inside  and  preserving 
its  purity. 

The  fusing  of  the  porcelain  may  be  known  either  by  watching  with 
the  eye,  or  by  gold  and  time  test,  as  previously  described,  in  which  the 
"plug"  closing  the  opening  of  the  muffle  may  be  frequently  removed  for 
the  purpose  of  observation,  and  the  same  requirements  incident  to  turn- 
ing off  the  heat,  and  allowing  the  work  to  cool  slowly  should  also  be 
observed. 

If  the  required  heat  is  to  be  obtained  with  facility,  the  supply  of  air 
must  not  be  allowed  to  become  diminished,  hence  the  pump  must  be  used 
with  sufificient  frequency  to  maintain  high  pressure. 

It  is  also  necessary  to  watch  the  condition  of  the  muffle  in  order  that 
it  may  be  replaced  when  the  continuity  becomes  destroyed  by  disintegra- 
tion, by  which  means  the  possibility  of  "gassing"  the  work  will  be  largely 
overcome ;  and,  the  greater  facility  with  which  this  may  be  done,  to- 
gether with  the  inclosed  shelf  at  the  opening  of  the  muffle,  for  heating 
the  work,  and  the  larger  size  of  the  latter,  constitute  the  main  advan- 
tages of  the  first-mentioned  furnace. 

The  gas  furnace  designed  by  Dr.  R.  C.  Brophy, 

Ga$  Turnaccs.  Fig.  210,  may  also  be  successfully  used.  As  a  sup- 
ply of  air  sufficient  to  afford  complete  combustion 
with  illuminating  gas  is  needed,  however,  the  employment  of  compressed 
air,  or  the  use  of  the  "bellows"  becomes  necessary,  and  in  the  absence 
of  the  former,  the  effort  required  is  of  course  much  greater  than  that  in 
the  use  of  gasoline.  Where  compressed  air  is  available,  this  furnace  is 
to  be  especially  recommended. 

The  more  or  less  objectionable  odor  which  emanates  from  the  use  of 
gasoline,  however,  is  overcome,  but  the  noise  produced  by  the  combus- 
tion in  each  is  one  of  the  most  unfavorable  features  in  connection  with 
the  use  of  either  of  these  furnaces, 


Tn$eilion  of  6oia  f illinas  in  Artificial  Cectb. 


CHAPTER  XIV. 

Indications.     Methods:  Foil  Gold,  "Roman"  Gold,   In   Combination  with  Backing; 

Procedure. 


The  insertion  of  gold  fillings  in  porcelain  facings  employed  in  the 
construction  of  crowns  and  bridges  is  very  often  indicated  as  a  means  of 
simulating  the  remaining  natural  teeth,  and  thus  observing,  and  complying 
with,  the  requirements  of  harmony,  and  with  a  view  to  and  for  the  purpose 
of  obtaining  increased  esthetic  and  artistic  results,  as  has  been  previously 
mentioned. 

In    the    construction    of   individual    crowns    for 
Indications.  any  of  the  anterior  teeth,  if  the  remaining  adjacent 

natural  teeth  are  more  or  less  freely  filled  with  gold, 
the  crown  should  almost  invariably  carry  one,  and  sometimes  two,  small 
approximal  fillings ;  and  in  bridgework  involving  the  upper  anterior  teeth, 
where  the  lower  anterior  teeth  are  likewise  filled,  the  insertion  of  one  or 
two  small  fillings  in  appropriate  locations  will  often  aid  materially  in 
detracting  from  the  artificial,  and  adding  to  the  natural,  appearance  of 
the  work. 

Such  fillings  should  never  be  inserted,  however,  with  a  view  of  making 
the  work  conspicuous,  nor  for  the  exclusive  purpose  of  additional  remu- 
neration, and  should  be  no  larger  than  necessary  to  effect  the  harmony 
and  legitimate  deceptioi  wliich  may  l)e  thtis  indicated  bv  the  adjacent 
natural  teeth. 

The  luethods  employed  in  accomplishing  this 
IttCtbOds.  work  consist  in  preparing  a  retentive  cavity  and  filling 

it  with  foil  gold ;  in  the  use  of  liquid  or  "Roman" 
gold,  which  is  painted  over  the  desired  area,  and  then  fired  in  the  furnace, 
in  a  manner  similar  to  that  employed  in  china  decorating;  and  the  con- 
struction of  the  filling  as  a  part  of  the  backing. 


28o 

In  the  emplo3'ment  of  this  method,  which  is  per- 

Toil  Gold.  haps  the  most  generally  used,  and  which  affords  the 

most  permanent,   expeditious  and  artistic  results,  a 

cavity,  in  the  appropriate  location  and  of  the  desired  form,  should  be  first 

outlined  in  the  facing  with  a  small  fine  carborundum-stone.    (Fig.  21  la.) 

This  outline  facilitates  the  cutting  or  drilling  of  a  cavity  of  the  neces- 
sary retentive  form  and  affords  a  definite  marginal  edge  for  the  subsequent 
adaptation  and  finishing  of  the  gold. 

When  so  formed,  adequate  retention  may  then  be  secured  by  drilling 
a  simple  countersunk  cavity  of  sufficient  proportions  in  the  center  of  the 
outlined  area   (Fig.  211b),  or  by  cutting  retentive  grooves   (Fig.  211c). 

For  the  former  purpose,  which  is  more  generally  applicable  to  small 
cavities,  an  inexpensive  diamond  drill,  to  be  used  in  the  engine,  is  made 
by  the  S.  S.  White  Dental  Manufacturing  Company  (Fig.  212a),  while 
the  retaining  grooves,  which  are  best  adapted  to  larger  cavities,  may  be 
easily  cut  with  a  small  copper  disk  coated  with  diamond  dust,  which  is 
also  prepared   for   this   and  similar  purposes    (Fig.   212b),  or  with  the 


b  c 

F/cj.211. 

"cavity  cutting"  outfit  manufactured  by  the  same  company,  and  which 
consists  of  a  set  of  engine  instruments  of  oval  form,  and  graded  sizes, 
and  a  cutting  material  composed  of  carborundum  dust  and  glycerol. 

While  this  latter  method  accomplishes  the  work  nicely,  it  is  scarcely 
so  expeditious  as  the  two  former  procedures,  in  the  use  of  which  the 
rapidity  of  their  cutting  properties  is  facilitated,  and  the  danger  of 
fracturing  the  facing  is  entirely  eliminated,  by  the  free  use  of  oil  or 
glycerine  as  a  lubricant.  This  saves  the  instrument,  and  prevents  the 
creation  of  heat  otherwise  induced  by  friction,  which  might  cause  fracture. 

When  the  proper  retention  has  been  secured,  the  cavity  should  be 
thoroughly  cleaned  with  soap  and  water  and  dried  with  alcohol  and  hot 
air,  and  then  filled  with  small  pellets  of  gold  in  the  ordinary  manner,  and 
finished  as  usual  (Fig.  21  id). 

While  it  is  usually  advisable  to  defer  the  insertion  of  such  fillings 
until  after  the  completion  of  the  work,  in  order  that  any  subsequent 
scratching  or  defacing  of  the  surface  may  be  prevented,  it  may  frequently 


28l 

become  necessary,  or  seem  desirable,  to  insert  them  before  the  construc- 
tion of  the  work,  or  the  assemblage  of  the  parts. 

This  may  be  essential  in  bridgevvork  constructed  with  gold  to  admit 
of  placing  the  cavity  in  the  desired  location  upon  the  approximal  surface, 
and  when  here  or  otherwise  indicated  the  procedure  may  be  greatly  facili- 
tated by  imbedding  the  facing  in  a  base  of  modelling  compound  or  sealing 
wax,  as  a  means  of  holding  it  securely  (Fig.  213). 

In  porcelain  work,  however,  the  procedure  must  necessarily  be 
deferred  until  the  piece  has  been  finished,  in  order  to  preclude  fusing  the 
gold,  and  the  same  is  likewise  advisable  in  single  crowns,  for  the  reason 
mentioned,  and  in  any  event  the  preparation  of  cavity  and  insertion  of 
filling  should  be  done  at  the  same  time. 


Ficj.  213. 


In  the  use  of  the  so-called  "Roman"  gold,  which 
Roman  Gold.  is  prepared  for  similar  decorative  purposes,  and  quite 

applicable  to  this,  the  cavity  area  should  be  first  out- 
lined, as  indicated  in  Fig.  211a,  and  the  gold  then  mixed  into  a  paste 
of  proper  consistency  and  painted  thickly  over  the  surface,  being  careful 
to  observe  that  it  closely  follows  and  evenly  approximates  the  cavity 
margins. 

The  facing  should  now  be  placed  near  a  Ranie,  or  close  to  the  previ- 
ously heated  furnace,  and  allowed  to  remain  until  the  gold  has  become 
thoroughly  dry,  when  it  should  be  placed  in  the  furnace  and  "fired"  until 
the  gold  fuses,  which  may  be  readily  observed  by  its  I'itrcous  appearance. 
After  allowing  to  cool  more  or  less  slowly,  the  filling  may  be  easily 
finished  and  polished  with  burnishers,  or  Unc  cuttle-fish  disks,  and  the 
bufif  wheel. 


282 

In  gold  work  such  fillings  should  be  made  before  the  final  attachment 
of  the  facing  to  the  metal  parts,  with  solder,  while  in  porcelain  work  the 
lower  heat  required  to  fuse  the  gold  demands  that  they  be  made  after  the 
completion  of  the  piece. 

While  this  method  affords  artistic  results,  the  objections  to  it  lie  in 
the  fact  that  such  fillings  are  likely  to  be  less  permanent,  because  of  a 
tendency  to  flake  and  chip. 

A   method   involving  a  less   simple   detail,   and 
Tn  Combination        requiring  more  time,  perhaps,  but  productive  of  very 

with  Baching.  artistic  results,  is  applicable  to  gold  work,  and  con- 

sists of  making  the  filling  in  combination  with  and 
as  a  part  of  the  backing. 

Its  employment  is  indicated  more  especially,  however,  in  simulating 
approximal  fillings  involving  the  incisal  angle,  which  is  sometimes  desir- 
able, and  which  would  be  more  or  less  difficult  by  the  other  methods. 


because  of  the  limited  opportunity  afforded  by  the  ordinary  facing  for 
securing  adequate  anchorage  for  such  fillings. 

When  such  a  filling   is    indicated,    or    where    it 

Procedure.  may  be  desirable  to  employ  this  method,  the  facing 

should  be  first  ground  to  the  proper  and   required 

adaptation,  and  then  prepared  for  the  reception  of  the  backing,  in  the 

usual  manner. 

That  portion  of  the  porcelain  which  involves  the  location  and  area 
of  the  desired  cavity  formation  and  gold  restoration  should  then  be  ground 
away  on  a  slight  bevel  toward  the  lingual  side,  until  a  perfectly  smooth 
marginal  outline  has  been  secured   (Fig.  214a). 

A  backing  of  about  34  gauge  pure  gold  should  now  be  adapted  to 
the  facing,  and  burnished  up  well  against  the  cavity  margin,  allowing  a 
surplus  of  about  1/32  of  an  inch  to  project  beyond  the  latter,  and  upon 
the  incisal  end  (Fig.  214b).  When  this  has  been  accomplished,  a  piece 
of  22  karat  gold  plate,  29  or  30  gauge,  should  be  adapted  to  this,  extend- 
ing from  the  pins  to  the  incisal  end,  and  projecting  out  to  the  original 


283 

outline  of  that  portion  of  the  facing  which  has  been  destroyed  (Fig. 
214c). 

This  forms  a  matrix,  indicating  the  desired  formation  of  the  filling, 
and  the  two  backings  should  now  be  removed  and  united  with  solder  in 
the  manner  previously  described  in  connection  with  "re-enforced  backings." 
Their  detachment  from  the  facing  without  danger  of  changing  the  shape 
of  the  thinner  one  is  made  possible  and  facilitated  by  the  slight  lingual 
bevel  given  to  the  cavity  wall  in  its  preparation. 

When  their  union  has  been  effected,  the  matrix  formed  by  the  two 
backings  should  be  filled  w^ith  22  or  20  karat  solder  until  the  desired 
contour  obtains  (Fig.  2i4d). 

This  should  then  be  adjusted  to  the  facing,  securely  attached  by 
bending  the  pins,  and  finished  with  files,  stones  and  disks  until  the  adapta- 
tion of  the  backing  and  the  contour  of  the  filling  are  as  desired  (Fig. 
2i4e),  when  the  piece  may  be  completed  and  finished  in  the  usual  manner. 

In  securing  the  desired  contour  of  the  filling  with  solder,  a  high 
karat  must,  of  course,  be  used,  because  of  the  susceptibility  to  discolora- 
tion, and  clean  flux  must  be  applied  to  avoid  a  pitted  surface. 

In  flowing  the  solder,  it  is  also  well  to  observe  the  precaution  of 
fitting  a  piece  of  gold  or  platinum  wire  or  plate  into  the  matrix  before  the 
procedure,  as  this  insures  a  preservation  of  the  adaptation  of  the  pure 
gold  to  the  cavity  margin,  which  otherwise  might  be  somewhat  changed 
by  shrinkage,  if  solder  alone  be  used. 


finishing,  Polisbing  ana  mounnng. 


CHAPTER  XV. 

Finishing.  Polishing :  Facilitating  Procedure.  Precautions.  Gold  Plating.  Cyan- 
ide Solutions,  Prepared  Solutions.  Mounting:  Preliminary  Adjustment; 
Temporary  Mounting;  Permanent  Mounting;  Use  of  Cement;  Procedure; 
Dowel  Crowns,  Shell  or  Telescope  Crowns,  Insuring  Accuracy  of  Adapta- 
tion to  Root,  Two  or  More  Crowns,  Therapeutics.  Use  of  Gutta  Percha ; 
Advantages,  Disadvantages,  Procedure ;  Dowel  Crowns,  Shell  or  Telescope 
Crowns,  Final  Mounting.  Combining  Cement  and  Gutta  Percha ;  Procedure. 
Variations  of  Procedure;  Use  of  Chloropercha ;  Use  of  Shellac  and  Sandarac; 
Rubber  Tissue.  Final  Precautions.  Removing  Crowns  Mounted  with  Gutta 
Percha. 


The  finishing,  poHshing  and  mounting  of  crowns,  while  almost 
equally  as  important  as  any  other  special  portions  of  the  work,  are,  never- 
theless, quite  often  neglected  or  done  in  a  more  or  less  perfunctory  man- 
ner, because  of  not  being  fully  appreciated. 

This  should  not  be  so  in  any  single  instance,  for  the  reason  that 
proper  finishing  and  polishing  adds  materially,  not  only  to  the  artistic 
appearance,  but  also,  and  particularly  where  gold  is  used,  to  the  increased 
hygienic  condition  presented  in  the  finished  piece ;  and  successful  mount- 
ing has  much  to  do  with  the  degree  of  comfort  and  permanency  of  the 
operation. 

TinisDing. 

When  the  case  has  been  removed  from  the  investment,  it  should 
first  be  treated  to  the  acid  bath  for  ?.  sufficient  length  of  time  to  insure  the 
thorough  removal  of  all  products  of  oxidation,  and  of  all  particles  of 
investment  material  and  "flux."  After  this  has  been  effectually  accom- 
plished, the  acid  should  be  thoroughly  removed  by  washing  freely  with 
clean  water,  and  the  case  then  finished  in  accordance  with  the  require- 
ments, and  with  the  maximum  of  artistic  possibilities  to  which  gold  and 
platinum  are  so  highly  susceptible,  as  is  evidenced  in  the  jeweler's  art, 
and  in  jeweler's  products. 

The  primary  efforts  in  finishing  should  consist  in  obtaining  the  re- 
quired contour;  the  desired  obliteration  of  all  joints,  and  evenness  and 


285 

smoothness  of  the  surfaces;  and  should  include  removing-,  or  diminish- 
ing any  undesirable  or  unnecessary  display  of  metal  upon  any  surface. 
Owing  to  the  small  size  of  the  piece,  this  may  usually  be  best  accom- 
plished with  small  carborunaum  stones,  of  coarse  and  medium  grit,  used 
in  the  engine.  These  should  oe  followed  with  emery  or  sandpaper  disks 
of  medium  grit,  and  subsequently  with  very  fine,  or  cuttlefish,  disks, 
until  every  scratch  is  removed,  and  the  surfaces  are  perfectly  smooth. 

A  more  finished  and  artistic  appearance  may  be  given  to  the  lingual 
surfaces  of  anterior  crowns  with  gold  backings  by  making  an  efifort  to 
reproduce  the  natural  shape  and  form  of  this  surface  in  the  gold  (Fig. 


Ficj.215. 


F/cf.2l6. 

215),  which  may  be  easily  and  quickly  done  with  a  knife-edge  carbo- 
rundum stone,  and  plug-finishing  burs. 


PoiisWnfl. 

This  should  then  be  followed  by  highly  polishing  the  metal  with  felt 
and  brush  wheels  on  the  lathe.  The  primary  polishing  should  be  ob- 
tained with  a  thin-edge  felt  wheel  (Fig.  216)  and  moistened  pumice  stone 
of  medium  grit ;  and  the  wheel  should  be  previously  soaked  in  water,  so 
that  it  will  absorb  and  carry  the  pumice  stone  with  it  during  the  proce- 
dure. 

When  the  desired  smoothness  of  surface  has  been  thus  obtained,  the 
final  polishing  should  be  given  first  with  a  stifif  brush-wheel  (Fig.  217a), 
used  with  the  pumice  stone,  and  then  with  moistened  whiting,  or  pre- 
cipitated French  chalk  ;   and  this  should  be  followed  with  a  soft  brush- 


286 


28; 

wheel  (Fig.  217b)  and  whiting,  and  finally  with  a  cotton  "buff"  wheel 
(Fig.  217c)   until  a  highly  polished  and  mirror-like  surface  presents 

Such  a  finish  requires  but  little  effort  and  but  a  few  moments'  time 
and  is  always  indicated  because  of  the  more  artistic  appearance  of  ':he 
work,  and  of  its  being  thus  rendered  more  hygienic.  The  more  highly 
the  surfaces  of  metal  are  polished,  the  less  susceptible  are  they  to  dis- 
coloration, and  the  more  permanent  and  self-cleansing  is  the  finish,  be- 
cause less  opportunity  is  thus  afforded  for  the  subsequent  attachment  of 
accumulations  in  the  mouth. 

Jewelers'  rouge  and  various  other  polishing  compounds  are  often 
advocated  and  are  employed  with  the  "buff"  wheel  for  the  final  polishing, 
but  nothing  seems   to  produce  better  results  than  whiting,  if  properly 


Fi^.  218. 


Fiq.219. 


used,  as  indicated  ;  and  the  reddish  color  imparted  by  rouge  to  the  metal, 
together  with  the  discoloration  of  the  fingers  incident  to  its  use,  are  more 
or  less  objectionable. 

As  single  crowns,  and  particularly  those  of  the 
Tacilitating  Procedure,     "shell  or  telescope"  variety,  are  somewhat  difficult  to 
handle  while  polishing,  various    styles    of    "crown- 
holders"  have  been  devised  for  facilitating  this  part  of  the  work. 

The  most  ingenious  and  perhaps  universally  useful  of  these  instru- 
ments is  the  one  known  as  Fahey's  Ideal  Crown  Holder,  manufactured 
by  the  Dental  Specialties  Company,  of  Chicago  (Fig.  218).  This  is  adapt- 
able to  almost  any  size  of  crown,  because  of  one  blade  being  removable; 


288 

and,  the  spring  being  adjustable,  it  holds  the  crown  securely  with  little  or 
no  danger  of  distorting  its  shape. 

A  similar  device  which  is  also  useful  for  this  purpose  is  known  as 
the  "Burgess"  crown  holders,  and  is  shown  in  Fig.  219. 

The  filling  of  the  crown  with  compounds  of  sealing  wax,  and  then 
mserting  a  piece  of  wood  into  it  while  it  is  hot,  is  sometimes  recom- 
mended, but  is  objectionable  because  of  the  difficulty  of  removing  the 
compound  after  the  polishing  is  completed ;  and  the  fitting  of  the  end  of 
a  piece  of  wood  of  suitable  length  to  the  interior  of  the  crown  is  likewise 
a  poor  method,  because  of  the  possible  distortion  of  the  shape  of  the  band 
in  so  doing. 

While  dowel  crowns  are  not  quite  so  difficult  to  handle  in  the  polish- 
ing, the  use  of  one  of  the  pin  vises  previously  recommended  may  some- 
times be  found  convenient. 

Although  it  is  scarcely  possible  to  give  too  high 

Precautions.  a  polish  to  the  exposed  surfaces  of  metal  which  are 

to  be  permanently  fixed  in  the  mouth,  it  is,  however, 
quite  possible,  and  indeed  sometimes  quite  easy,  to  polish  through  the 
thinner  portions  of  a  crown  in  the  use  of  disks  and  felt  wheels ;  hence, 
in  polishing,  extreme  care  should  be  exercised  to  prevent  such  a  mishap, 
as  well  as  to  preclude  any  unnecessary  thinning  of  such  parts. 

6oia  Plating. 

An  increased  artistic  effect,  and  a  more  permanent  finish,  may  be 
obtained  by  subjecting  the  piece  to  the  electroplating  process,  after  it  has 
been  highly  polished.  This  imparts  a  uniform  rich  yellow  color  to  all 
metal  surfaces  and  afifords  a  surface  of  pure  gold  which  is  more  or  less 
permanent,  and  which  is  not  so  easily  attacked  and  discolored  by  the 
chemical  action  of  the  secretions. 

Solutions  for  this  purpose  may  be  made  by  dis- 
CVanidC  Solution.  solving  fifteen  grains  of  the  chloride  of  gold  in  a 
porcelain  or  glass  vessel  containing  about  four 
ounces  of  distilled  water,  and  then  adding  to  this  a  like  (luantity  of  water 
into  which  about  thirty  or  forty  grains  of  pulverized  potassium  cyanide 
has  also  been  previously  dissolved  in  a  similar  vessel.  This  is  known  as 
the  "cyanide  solution,'"  the  approximate  formula  for  which,  as  generally 
employed,  is  as  follows : 

Chloride  of  gold  gr.     xv. 

Cyanide  of  potassium      gr.  xxx.  to  xl. 
Distilled  water  oz.  viii. 

A  small  ordinary  "primary"  or  "dry  cell"  battery  may  be  used,  and 
the  work  to  be  plated  should  be  attached  to  the  negative  pole  and  then 


289 

suspended  in  the  solution,  with  a  piece  of  thin  pure  gold  plate  likewise 
suspended  from  the  positive  pole,  avoiding  contact  between  the  two. 

If  the  piece  is  well  finished  and  highly  polished,  and  then  washed 
with  bicarbonate  of  sodium  to  remove  all  traces  of  organic  matter,  and 
then  fastened  to  the  pole  by  so  coiling  the  wire  as  to  have  a  well-distrib- 
uted contact  over  the  surface  of  the  metal  to  be  plated,  a  few  minutes' 
immersion  in  the  solution  will  afford  the  desired  result,  after  which  it 
should  be  again  highly  polished  with  the  "huff"  wheel. 

Solutions  which  may  be  used  without  a  battery 
Prepared  Solutions,     are  prepared  for  this  purpose,  and  while  they  seem 
to  afford  good  results,  the  deposit  of  gold  is  prob- 
ably not  so  heavy,  and  hence  not  so  permanent,  and  the  solution  can  only 
be  used  until  it  becomes  inactive. 

In  their  use  a  sufficient  quanity  of  the  solution  should  be  placed  in 
a  porcelain  or  glass  vessel  and  heated  until  zvarm,  and  the  work  then  at- 
tached to  a  strip  of  pure  zinc  and  immersed  therein. 

Moderate  heat  and  slight  agitation  will  effect  the  desired  result  in  a 
few  moments,  and  the  permanency  and  effectiveness  of  the  solution  may 
be  increased  by  suspending  a  small  piece  of  pure  gold  plate  on  another 
zinc  strip  hooked  over  the  edge  of  the  vessel  so  that  the  gold  is  immersed. 

No  portion  of  the  entire  procedure  incident  to  the  construction  and 
application  of  the  work  is  of  more  importance  than  the  detail  involved 
in  its  secure  and  permanent  attachment  to  the  root. 

In  order  that  such  a  fixation  may  be  secured  with  reasonable  facility, 
the  medium  used  must  possess  sufficient  plasticity  to  admit  of  the  proper 
and  accurate  adjustment  of  the  crown,  and  to  completely  fill  the  interven- 
ing space  between  it  and  the  root,  and  must  then  afford  a  substantial  and 
more  or  less  insoluble  and  impervious  union  between  the  two. 

Previous     to     any     effort     toward     permanent 

rreiimmary  mounting,  the  crown  should  ahvays  be  adjusted  to 

ifajustmcnt.  •,•  .1         .  /         ,  •  •         •, 

position  on  the  root,  as  a  means  of  ascertaining  with 

absolute  certainty  that  it  meets  with  all  the  requirements  of  fit,  occlu- 
.sion,  etc.,  as  well  as  to  admit  of  making  any  changes  in  its  form  or  shape 
which  may  be  necessary,  and  of  subsequently  repolishing,  which  can 
never  be  done  so  well  after  permanent  fixation  is  secured. 

The  adjustment  may  be  greatly  facilitated  in  so  far  as  discomfiture 
to  the  patient  is  concerned  by  slightly  moistening  the  interior  of  the  band 
with  95  per  cent  carbolic  acid,  or  by  carefully  bathing  the  gum  surround- 
ing the  root  with  a  two  or  a  four  per  cent  solution  of  cocaine  just  pre- 
vious to  inserting  the  crown. 


290 

The  former  procedure  is  perhaps  the  more  simple,  equally  effective 
and  less  dangerous  one,  and  usually  affords  sufficient  anesthesia  of  the 
parts  to  admit  of  the  subsequent  permanent  mounting  without  any  ap- 
preciable discomfiture;  and  any  possible  injury  to  the  tissues  from  the 
escharotic  effect  may  be  overcome  by  bathing  them  with  alcohol  as  soon  as 
the  crown  is  forced  to  place. 

The  driving  of  the  crown  to  position  is  never  warrantable  or  neces- 
sary if  the  adaptation  is  anywhere  near  correct;  anterior  crowns  can 
usually  be  forced  to  place  with  the  fingers,  and  a  firm  closure  of  the  jaw 
will  aid  in  adjusting  those  on  the  posterior  teeth.  In  the  event  of  the 
absence  of  occluding  teeth,  a  small  flat  piece  of  wood  may  be  used  to 
advantage  here,  as  indicated  in  the  fitting  of  bands. 

When  it  has  been  observed  that  the  adaptation  is  correct,  the  crown 
should  be  then  removed  and  mounted,  as  the  patient  should  never  be  dis- 
missed, no  matter  Jiozv  firm  it  may  remain  in  place  at  first,  without  th« 
presence  of  some  medium  of  attachment  which  may  preclude  its  becom- 
ing loosened,  and  any  possible  distortion  of  the  fit  or  shape  which  might 
result  therefrom  in  wearing,  not  overlooking  the  danger  of  swallowing  it. 

Cemporary  mountiitd. 

In  the  event  of  permanent  mounting  being  contraindicated  for  a 
time,  the  crown  may  be  temporarily  mounted  in  a  manner  which  will  ad- 
mit of  its  being  worn  without  danger  of  becoming  loosened  or  distorted  in 
shape,  and  of  its  being  removed  with  facility  whenever  necessary. 

When  such  a  procedure  may  for  any  reason  be  indicated,  temporary 
stopping  will  serve  as  a  sufficiently  substantial  medium  to  afford  attach- 
ment from  sitting  to  sitting,  or  for  a  few  days'  duration,  but  it  does  not 
possess  sufficient  integrity  to  be  reliable  for  any  great  length  of  time. 

In  its  use,  the  root  should  be  dried  with  alcohol  and  hot  air,  and  a 
sufficient  quantity  thoroughly  heated  and  placed  inside  of  the  band,  and 
the  crown  then  quickly  forced  to  place,  after  which  it  may  be  chilled  with 
a  spray  of  cold  water  directed  upon  the  crown,  and  the  surplus  then 
trimmed  away. 

Crowns  so  mounted  may  be  easily  removed  with  a  pointed  instru- 
ment, hooked  over  the  edge  of  the  band,  as  heat  higher  than  the  temper- 
ature of  the  body  is  scarcely  ever  necessary  to  destroy  or  reduce  the  ad- 
hesive property  of  this  material,  which  accounts  for  its  not  being  reliable 
for  more  permanent  usage. 

Permanent  mounting. 

The  rcfjuircments  of  a  j)ermancnt  mounting  are  best  obtained  at  the 
present  time  in  the  use  of  the  oxyphosphatc  of  zinc  cements  and  gutta 


291 

percha.  Amalgam  was  formerly  used  to  some  extent  but  has  beerx  prac- 
tically abandoned  in  view  of  the  greater  facility  with  which  either  of  these 
ma}'  be  successfully  employed,  and  the  absence  of  adhesive  properties. 


Use  of  €ciiieRt. 

Cement  is  perhaps  the  more  generally  employed  because  of  the  facility 
with  which  it  may  be  manipulated,  combined  with  its  adhesive  properties 
and  inh'='rent  strength  when  moisture  is  excluded. 


Fiq.  220. 

The  disadvantages  incident  to  its  use  are  the  temporary  irritation  to 
the  tissues  in  mounting;  the  possible  more  or  less  permanent  irritation 
which  may  be  induced  by  hidden  particles  accidentally  left  in  contact 
with  the  gum  after  mounting ;  its  susceptibility  to  dissolution  when  ex- 
posed to  the  action  of  the  secretions  ;  its  possible  shrinkage  in  crystallizing, 
and  the  extreme  difficulty  with  which  a  crown  may  be  removed,  and  par- 
ticularly a  dowel  crown,  when  occasion  demands. 


292 

When  it  has  been  ascertained  that  the  adapta- 
Prwcdurc.  tion  is  correct,  and  when  the  crown  is  ready  to  be 

permanently   mounted,    its   inner   surface   should   be 
cleansed  with  alcohol,  and  thoroughly  dried  with  hot  air. 

The  root  should  now  be  rendered  aseptie  by  a  careful  bathing  with 
carbolic  acid,  or  by  the  use  of  pyrozone  or  hydrogen  peroxide,  or  any 
good  antiseptic,  and  then  thoroughly  dried  with  pledgets  of  cotton. 

Thorough  drying  is  absolutely  essential  and  may  be  facilitated  by 
precluding  contact  of  the  lips,  cheeks,  or  tongue,  with  cotton  rolls  or  pads, 
and  then  using  alcohol  or  chloroform  evaporated  with  compressed  air,  or 
warm  air  from  the  chip  blower.    The  non-absorbent  cotton  rolls  prepared 


^^7.  ^^/, 


in  various  sizes  and  lengths  by  Johnson  and  Johnson  are  very  convenient 
for  such  purposes.  The  use  of  these  in  the  anterior  part  of  the  mouth 
is  illustrated  in  Fig.  220,  and  if  the  root  is  in  the  posterior  part  of  the 
mouth,  a  "mouth  prop"  adjusted  in  the  opposite  side  to  hold  the  mouth 
open  will  often  be  found  very  useful,  and  the  cotton  rolls  may  be  effec- 
tively retained  with  a  clamp  adjusted  to  an  adjacent  tooth.     Fig.  221. 

A  good  reliable  medium  setting  cement  should  now  be  mixed  to  a 
creamy  consistency,  which  should,  and  can  best,  be  done  by  an  assistant, 
when  possible,  in  order  that  the  operator  may  confine  himself  to  observing 
that  the  root  docs  not  become  moistened. 


293 

If  the  crown  possesses  a  dowel,  the  canal,  or 
Dowel  €r0Wtt$.  canals,  should  first  be  thoroughly  filled  with  the 
cement.  This  may  be  accomplished  by  using  a  root 
canal  plugger  and  a  pumping  action,  until  the  cement  has  been  carried  to 
the  extreme  ends.  A  cement  syringe  for  this  purpose  has  been  devised 
by  Dr.  H.  L.  Cruttenden,  but  its  use  usually  involves  more  time  than  is 
necessary  or  warrantable  for  such  a  simple  procedure. 

When  the  canal  has  been  thus  well  filled,  the  dowel  and  interior  of 
the  cap  should  be  coated  or  covered  with  a  layer  of  cement,  which,  if 
done  by  the  assistant  during  the  filling  of  the  canal,  will  greatly  expedite 
the  operation,  and  the  crown  should  then  be  quickly  and  firmly  pressed 
to  its  proper  position  on  the  root. 

After  becoming  assured  of  its  having  assumed  the  proper  relation, 
the  patient  may  be  requested  to  close  the  mouth  until  the  cement  has  at 
least  partially  crystallized,  the  length  of  time  required  for  which  will  be 
indicated  by  the  surplus  remaining  upon  the  mixing  slab.  It  is  desir- 
able that  the  first  stages  of  the  setting  of  the  cement  should  be  obtained 
under  pressure.  Therefore  the  operator  should  press  firmly  upon  the 
crown  with  the  finger  or  a  piece  of  soft  wood  for  at  least  five  minutes. 

The  crystallization  may  be  hastened  somewhat  by  directing  warm 
air  from  the  chip  blower  upon  the  crown,  and  when  sufficiently  hard,  all 
surplus  should  be  carefully  removed  with  pledgets  of  cotton,  and  a  sharp- 
pointed  explorer  passed  carefully  around  the  band  beneath  the  gum. 

A  ligature  drawn  through  the  interproximal  space  may  further  in- 
sure the  removal  of  any  remaining  surplus  at  these  points,  which  precau- 
tions are  always  advisable,  because  of  the  extreme  irritation  to  the  gum 
which  is  produced  by  such  hidden  particles  after  their  complete  crystalli- 
zation. 

Coating  the  outside  of  the  band  along  the  cervix  with  vaseline  or  oil 
just  previous  to  mounting  is  recommended  as  a  means  of  facilitating  the 
removal  of  the  excess  by  preventing  its  adhering  to  the  edge  or  surface  of 
the  crown. 

In  mounting  the  "shell  or  telescope"  crown,  the 
"Shell  or  same  detail  is  indicated,  but  as  a  larger  quantity  of 

CekSCOpe"  Crowns,    cement  must  be  placed  in  the  crown,  care  should  be 
exercised  to  have  it  cover  all  surfaces,  and  be  devoid 
of  air  spaces,  in  order  to  insure  the  complete  filling  of  the  entire  interven- 
ing space  between  it  and  the  root.     The  proper  quantity  is  governed,  of 
course,  by  the  length  of  the  root  which  projects  or  extends  into  the  crown. 

As  soon  as  the  crown  is  forced  to  place,  the  mouth  should  be  imme- 
diately closed  and  the  occlusion  observed,  and  when  this  is  as  it  should 
be,  which  will  be  indicated  by  the  normal  contact  of  the  adjacent  oppos- 


294 

ing  natural  teeth,  a  roll  of  cotton  should  be  placed  between  the  crown 
and  the  opposing  teeth,  and  a  steady  and  firm  pressure  of  the  jaw  in 
normal  occlusion  maintained  until  the  cement  has  crystallized,  in  order  to 
prevent  any  possible  displacement. 

The  same  precautions  incident  to  the  removal  of  all  excess  cement 
should  then  be  observed  with  equal  tare,  and  before  dismissing  the  patient 
it  should  be  carefully  and  finally  noted  that  the  crown  does  not  occlude 
too  hard,  as  subsequent  discomfiture  will  invariably  result  if  this  con- 
dition exists. 

If  any  doubt  exists  as  to  the  accuracy  of  the  re- 
Tniurinfl  JlCCUracy  of    lation  of  the  cervical  edge  of  the  crown  to  the  per- 
Jldaptatien  to  Root,     iphery  of  the  root,  some  means  of  insuring  a  close 
joint  between  them  should  be  observed. 
This  may  often  be  aided  materially  by  slightly  reducing  the  circum- 
ference of  the  edge  of  the  band  with  curved  or  small,  pointed  pliers,  just 


Ficj.222. 


previous  to  the  final  mounting,  as  it  may  have  become  somewhat  en- 
larged, by  stretching,  in  the  fitting  and  preliminary  trials. 

The  use  of  a  smooth  foot  plugger  adjusted  to  the  automatic  mallet 
may  also  be  found  useful,  and  particularly  along  the  buccal  edge,  after 
the  crown  has  been  mounted ;  and  the  approximal  edges  may  be  brought 
into  closer  contact  by  inserting  a  small  amalgam  burnisher  into  the  inter- 
proximal spaces,  and  exerting  some  little  effort  in  this  direction.  Either 
a  suitable  burnisher,  such  as  is  illustrated  in  Fig.  222,  or  the  foot-plugger, 
may  often  be  employed  to  good  advantage  upon  the  lingual  surface,  but 
in  the  use  of  either,  some  little  care  should  be  observed  to  avoid  produc- 
ing sharp  angles  at  the  corners,  and  yet  to  secure  a  close  adaptation  and 
particularly  at  the  bifurcation  of  the  roots. 

In  extreme  cases  of  ill  adaptation  or  of  exceedingly  constricted 
necks,  a  good  result  may  often  be  obtained  by  encircling  the  crown  with 
a  piece  of  German  silver,  or  copper  wire,  from  24  to  26  gauge,  passed 
through  the  interproximal  spaces,   and  the  ends  then  twisted  from  the 


295 

buccal  side,  until  the  loop  breaks.  This  affords  a  uniform  compression 
of  the  edge  of  the  band  by  condensing  the  molecules,  but  in  eft'ecting  it, 
it  should  be  observed  that  the  wire  does  not  slip  beneath  the  edge  of  the 
band,  which  tendency  may  be  overcome  by  slightly  flattening  that  portion 
which  rests  against  the  Ungual  surface  of  the  crown,  or  which  forms  the 
center  of  the  loop.  While  ordinary  silver  suture  wire,  or  that  made 
from  other  alloys  or  metals  may  be  used,  those  recommended  give  the 
best  results  because  of  their  tensile  strength. 

Wherever  possible,  all  of  these  procedures  should  be  observed,  or 
executed,  after  the  crown  has  been  properly  mounted,  and  a  firm  closure 
of  the  jaw  should  be  maintained  in  order  to  prevent  lifting  it  from  its 
proper  relation.  The  cement  should  first  be  allowed  to  become  partially 
crystallized,  also,  in  order  that  any  slight  hemorrhage  produced  may  in- 
terfere as  little  as  possible  with  its  perfect  crystallization. 

When  two  or  more  crowns  are  to  be  inserted  at 
CWO  or  more  Crowns,    the  same  sitting,  each  should  he  mounted  separately, 

as  the  crystallization  of  the  cement  seldom  aft'ords 
opportunity  for  the  thorough  and  accurate  mounting  of  more  than  one 
with  each  mixing;  and  the  operator  should  never  be  hurried,  nor  make 
any  effort  to  expedite  matters  to  too  great  an  extent  in  this  procedure. 

In  cases  of  extreme  pain  after  mounting,  which 
tberapCUtiCS.  is  sometimes   induced  by  the  irritating  influence  of 

the  cement  upon  inflamed  or  hypersensitive  tissues, 
but  which  is  usually  only  temporary,  relief  may  be  afforded  by  painting 
the  gums  around  the  neck  of  the  crown  with  a  two  or  a  four  per 
cent,  solution  of  cocaine ;  or  with  the  tincture  of  iodine,  or  the  usual  rem- 
edies for  counter-irritation.  A  spray  of  hot  water  is  also  sometimes  very 
efi'ective,  and  where  an  astringent  may  be  indicated,  in  cases  of  con- 
gestion, zinc  sulphate  or  a  saturated  solution  of  tannic  acid  in  glycerine 
may  be  employed. 

Use  of  Gutta  PcrcDii. 

The  difficulty  encountered  in  the  removal  of  crowns  mounted  with 
cement,  and  particularly  of  dowel  crowns,  has  created  a  demand  for  some 
medium  which  would  afford  a  secure  and  reliable  attachment,  and  which 
would  at  the  same  time  admit  of  subsequent  removal  in  the  event  of 
necessity,  without  requiring  the  destruction  of  the  crown  or  of  any  ap- 
preciable amount  of  tooth  structure. 


296 

The    ordinary    red    or    pink    base-plate    gutta 

TfdPantagCS,  percha,    skilfully   manipulated,    seems   to   meet   such 

requirements  in  admitting  of  easy  removal,  as  well 
as  to  possess  the  additional  desirable  qualities  of  offering  sufificient  in- 
tegrity in  the  attachment,  and  of  being  insoluble,  non-irritating,  and  more 
or  less  impervious. 

Its  use  also  affords  a  somewhat  cushion-like  seat  for  the  crown, 
which  is  an  advantage  because  of  relieving  the  "deadened  blow"  in  the 
stress  of  mastication,  and  of  thus  reducing  the  shock,  and  diminishing 
the  tendency  of  porcelain  to  fracture,  as  compared  with  a  more  non- 
yielding  medium. 

The  disadvantages   incident  to  the  employment 
Disadvantages.  of  this  material  lie  mainly  in  the  skill  and  time  re- 

quired to  successfully  manipulate  so  refractory  or  in- 
tractable a  substance ;  and  yet  its  integrity  as  a  substantial  mounting  is 
due  to  such  properties,  and  will,  of  course,  increase  in  proportion  thereto, 
so  long  as  it  is  capable  of  being  rendered  sufficiently  plastic  to  be  properly 
moulded,  in  the  adjustment  of  the  crown. 

While  its  employment  is  probably  more  especially  indicated  for  dowel 
crowns,  this  same  essential  property  may  here  prove  a  disadvantage,  if 
any  great  surplus  is  present,  by  offering  sufficient  resistance  to  expand 
the  band,  and  thus  destroy  the  accuracy  of  its  adaptation. 

This  objection  may  be  overcome,  however,  by  careful  manipulation 
in  obtaining  the  maximum  of  plasticity,  and  avoiding  the  presence  of  any 
unnecessary  surplus.  Successful  results  will  depend  upon  a  willingness 
to  consume  time,  and  to  observe  the  detail  with  deliberate  painstaking 
care,  as  well  as  in  the  acquirement  of  the  necessary  degree  of  skill ;  and 
will  increase  in  proportion  thereto. 

In  its  manipulation,  the  material  should  be  cut 

Procedure.  ""ito  narrow  shreds  or  strips,  from  one-half  to  one 

inch  in  length,  and  these  should  then  be  slowly  and 
carefully  heated  until  ])lastic.  The  heating  should  be  done  at  the  chair, 
and  may  be  best  accomplished  by  placing  them  on  a  porcelain-lined 
electric  gold  annealer,  such  as  is  manufactured  by  Mr.  M.  M.  Kerr, 
of  Detroit,  Mich. ;  or  upon  a  mica  slab  placed  over  a  flame,  where  they 
should  remain  until  the  nicnniting  is  c()mi)leted.  The  Custer  electric  gold 
annealer  has  an  accompanying  porcelain  slab  which  may  also  be  used 
for  this  purpose. 


297 

Direct  contact  with  the  flame  should  ahvays  be  avoided,  as  this  de- 
stroys the  working  properties  of  the  material  by  rendering  it  harsh  and 
tough. 

While   the   gutta   percha   is   being  thus   heated, 

Dowel  Crowns.         the  dowel  of  the  crown  should  be  spurred  with  a 

sharp  knife-blade,  and  it  and  the  interior  of  the  cap 

then   slightly  moistened  with   a   solvent  of  gutta  percha  to   facilitate  a 

secure  attachment.     Oil  of  cajeput  is  probably  the  best  solvent  for  this 

purpose,  though  oil  of  eucalyptol  or  chloroform  may  be  used. 


When  thus  prepared,  a  piece  of  the  gutta  percha  should  be  picked 
up  with  foil  carriers,  coiled  around  the  dowel  from  its  apex  downward. 
Fig.  227,  A,  and  then  packed  down  closely  with  the  fingers.  If  one  piece 
does  not  appear  to  be  sufficient  for  the  first  trial,  another  may  be  added, 
until  what  seems  to  be  adequate  is  obtained,  but  a  surplus  should  be 
avoided. 

The  crown  should  now  be  placed  upon  the  heater,  and  the  canal  and 
end  of  the  root  then  moistened  with  a  spray  of  water  from  a  syringe,  in 
order  to  prevent  the  gutta  percha  from  adhering,  after  which  the  heated 
crown  may  be  grasped  with  a  napkin  and  forced  to  position.  If  no  great 
surplus  has  been  used,  it  will  go  readily  to  place  without  driving,  when 
it  should  be  at  once  removed,  and  small  pieces  of  the  heated  material 
added,  where  needed ;  it  is  then  placed  again  upon  the  heater,  the  root 
moistened,  and  this  procedure  continued  until  the  gutta  percha  is  moulded 
to  fill  the  space  between  crown  and  root,  when  the  correct  relation  exists. 

All  surplus  should  now  be  trimmed  oflf  even  with  the  edge  of  the 
band,  and  the  crown  then  replaced  upon  the  heater. 


298 

In  the  event  of  the  presence  of  too  much  gutta  percha  to  admit  of 
the  proper  adjustment,  the  surphis  should  be  trimmed  away  with  a  hot  in- 
strument, and  the  crown  reheated  and  carried  to  place,  until  the  proper 
relation  maintains. 

The  procedure  indicated  in  the  mounting  of  the 

Sbcll  Of  "shell  or  telescope"  crown  is  the  same,  except  that 

telescope  €rown$.       the  gutta  percha  may  be  cut  into  small  square  pieces, 

of  convenient  size ;  and  these  should  be  placed  in  the 

bottom  of  the  crown  and  around  the  joint  between  cusp  and  band,  until 

they  may  be  gradually  moulded  to  fill  the  space. 

Up  to  this  point,  the  root  should  be  moistened 
Tinal  mounting.        previous  to  each  application  or  trial  of  either  style 
of  crown,  in  order  that  its  removal  may  be  made 
easy  by  preventing  adhesion. 

When  ready  for  the  final  mounting,  the  crown  should  be  again 
placed  upon  the  heater,  and  allowed  to  remain  until  the  root  has  been 
rendered  aseptic,  and  then  thoroughly  dried  in  the  manner  indicated  in 
connection  with  cement.  It  should  now  be  moistened  with  the  oil  of 
cajeput,  or  with  a  thin  solution  of  chloropercha,  and  the  crown  then 
picked  up  with  a  napkin,  and  forced  to  place,  where  it  should  be  held 
firmly  for  a  few  moments,  until  the  gutta  percha  loses  its  heat,  which 
may  be  hastened  by  a  spray  of  cold  water. 

Comoinitid  Cement  and  6uttd  Percha. 

While  either  cement  or  gutta  percha  may  be  used  in  mounting  shell 
or  telescope  crowns,  on  the  posterior  teeth,  the  advantages  of  both  may 
be  obtained  for  dowel  crowns  by  combining  them.  This  may  be  done  in 
such  manner  as  to  admit  of  the  subsequent  removal  of  the  dowel,  in  case 
of  accident  or  necessity  without  any  great  difficulty,  and  to  overcome  any 
possible  danger  of  enlarging  the  narrow  band,  such  as  may  possibly  result 
from  the  use  of  gutta  percha  alone. 

Whatever  advantages  cement  may  possess  as  a  mounting  medium, 
it  is  seldom  the  best  practice  to  surround  the  dowel  exclusively  with  this 
material  because  of  the  extreme  difficulty  of  ever  removing  it  from  the 
root.     Hence,  if  one  is  not  sufficiently  skilled  in  the  manipulation  of  gutta 


299 

percha  alone,   some  means   of  facilitating  the   removal  of  such   crowns, 
without  injm-y  to  the  root,  is  always  indicated. 

This   may   be   accomplished   by   using   sufficient 

Procedure.  gutta  percha,  in  the  manner  described,  to  surround 

the  dowel  only    (Fig.  223   B)    and  then  completing 

the  mounting  by  filling  the  cap  and  coating  the  walls  of  the  canal  with 

cement,  thus  obtaining,  in  a  measure,  the  advantages  of  both,  with  the 

minimum  of  the  objections  of  each. 

Various  combination  cements  in  which  gutta  percha  filings,  or  gutta 
percha  in  solution,  is  incorporated  with  the  oxy-phosphate  of  zinc,  are 
advocated,  but  as  their  use  is  at  present  somewhat  experimental  they  are 
not  recommended. 

Uarlatlotis  of  Procedure. 

The  skill  required  to  successfully  manipulate  gutta  percha  has  caused 
the  adoption  of  several  variations  of  procedure,  each  with  a  view  of  ac- 
complishing the  desired  result  with  greater  facility  and  expediency. 

A  thick  solution  of  gutta  percha  in  chloroform 
U$C  Of  Cbloropcrcba.  is  sometimes  employed  for  the  entire  mounting  of 
dowel  crowns,  but  is  not  recommended,  because  of 
the  shrinkage  of  such  medium,  due  to  the  evaporation  of  the  chloroform. 
This  shrinkage  will,  of  course,  afford  some  opportunity  for  the  subsequent 
loosening  of  the  crown,  and  thus  diminishes  the  stability  and  permanency 
of  the  attachment. 

It  may  be  used  around  the  dowel  and  on  the  inner  surface  of  the  cap, 
however,  in  place  of  the  base-plate  gutta  percha,  and  when  so  employed, 
the  chloroform  should  first  be  evaporated  by  passing  over  a  flame,  and 
the  crown  then  mounted  with  cement,  as  indicated.  This  prevents  the 
adhesion  of  the  cement  to  the  surfaces  of  the  dowel  and  cap,  which,  of 
course,  facilitates  the  removal  of  the  crown,  but  not  to  the  extent  aflforded 
by  the  use  of  the  gutta  percha  alone,  when  it  entirely  fills  the  canal. 

A  heavy  coating  of  shellac  or  sandarac  varnish 
Shellac  and  Sandarac     of  ^   ^hick   consistencv   will   also  prevent   the   adhe- 

Uarnisb.  ,  ,,,,,,•      r    m  .  . 

sion  of  cement  to  the  dowel,  and  likewise  lacilitate 

the  removal  of  the  crown. 


30O 

An  antiseptic   rosin  compound  has  been  intro- 

DodCZ'  Rosin  duced  under  the  name  of  Onilite,  and  is  advocated 

Compound. 

by  Dr.   E.  W.  Dodez,  of   Fort  Wayne,   Ind.     This 

preparation  is  highly  antiseptic;  melts  at  a  point  just  high  enough  not 
to  be  affected  by  the  temperatures  of  the  mouth ;  is  very  adhesive,  cools 
quickly,  is  easily  manipulated  and  seems  very  useful,  particularly  for 
telescope  crowns. 

A  preparation  of  rubber  in   the   form  of  very 
Rubber  ti$$U(.  thin  tissue,  which  is  quite  adhesive,  is  recommended 

for  similar  use  by  Dr.  W.  F.  Lawrenz,  of  St.  Louis, 
but  at  the  present  stage  of  its  experimental  application,  it  seems  to  offer 
no  particular  advantages  over  the  preceding  materials,  and  is  more  diffi- 
cult to  manipulate. 

Tinal  Prcc<)ution$. 

When  the  mounting  has  been  completed  with  apparent  satisfaction, 
the  patient  should  never  be  dismissed  until  it  has  been  carefully  ascer- 
tained that  the  crown  is  firm,  and  that  the  occlusion  and  all  surrounding 
conditions  are  favorable ;  and  a  further  precaution  against  any  possible 
subsequent  displacement,  annoyance  or  discomfiture  should  be  observed 
by  requiring  the  patient  to  return  in  the  course  of  a  few  days  for  final 
inspection. 

K^movind  £rown$  mounted  witb  Gutta  Pcrcba. 

The  removal  of  crowns  mounted  with  gutta  percha  may  be  easily 
effected  by  applying  sufficient  heat  to  the  exposed  portion  of  the  crown 
to  soften  the  material.  This  may  be  done  by  heating  the  beaks  of  a 
pair  of  heavy  pliers  of  good  size,  placing  them  on  the  crown,  and  sus- 
taining the  contact  until  the  heat  is  conveyed  throughout  its  length, 
which  will  usually  be  noted  by  a  response  from  the  patient,  when  the 
gutta  percha  surrounding  it  will  be  sufficiently  softened  to  lose  some  of 
its  adhesive  properties,  and  admit  of  the  ready  detachment  of  the  crown 
with  a  hooked  or  pointed  instrument. 

In  this  procedure,  care  should  be  exercised  to  guard  the  face  and 
lips  of  the  patient,  as  well  as  to  protect  the  porcelain,  which  may  be  aided 
by  cotton  rolls  or  pads ;  and  the  pliers  should  be  heated  in  the  laboratory, 


30I 

or  where  the  heating  may  not  be  observed  by  the  patient,  and  then  car 
ried  to  the  chair  wrapped  in  a  napkin  or  towel,  with  only  the  beaks  ex- 
posed, as  a  matter  of  convenience  to  the  operator,  and  of  protection  and 
relief  from  fear  to  the  patient. 

A  more  convenient  method  which  may  sometimes  be  emploved  with 
success  has  been  suggested  by  Dr.  C.  B.  Rohland.  This  consists  in 
placing  a  leather  or  moose-hide  polishing  wheel  in  the  engine  and  re- 
volving it  with  rapidity  against  the  crown  until  the  friction  will  thus 
produce  sufficient  heat  to  admit  of  its  removal. 


Accuracy  in  model  lllaKing. 


CHAPTER  XVI. 


Whilst  much  emphasis  has  already  been  placed  upon  the  necessity  for 
accuracy  in  impression  taking  and  model  making,  these  features  of  the 
procedure  are  of  such  paramount  importance  as  to  make  special  emphasis 
warrantable. 

Throughout  the  entire  procedure  incident  to  the  construction,  or  even 
the  repair,  of  any  style  of  crown,  and  particularly  of  those  for  the  anterior 
teeth,  a  good  impression  and  an  accurate  model  are  prerequisites  to  suc- 
cess, because  by  this  means  the  work  may  be  transferred  from  the  mouth 
to  the  laboratory  with  all  the  exactness  which  successfvil  achievement 
demands. 

In  order  that  the  very  best  results  may  be  obtained  with  the  greatest 
degree  of  accuracy  and  expediency,  the  impression  should  always  be  taken 
in  plaster  because  of  its  being  the  most  reliable  material ;  and  the  model 
obtained  from  it  must  support  and  sustain  the  cap — or  caps — in  the  proper 
and  exact  relation  which,  when  in  the  mouth,  they  bear  to  the  roots,  to  the 
adjacent  teeth,  and  to  the  gingival  outline  of  the  tissues. 

The  facility  with  which  the  cap,  or  caps,  may  be  detached  or  removed 
from  the  model — and  in  such  manner  as  to  admit  of  ready  and  accurate 
readjustment — depends  largely  upon  the  observation  of  the  detail  of  filling 
the  interior  of  the  cap,  and  covering  the  dowel,  with  a  thin  film  of  melted 
wax  just  previous  to  filling  the  impression,  as  is  illustrated  in  Fig.  224  A 
for  a  lateral  and  in  Fig.  224  P>  for  a  bicuspid  crown. 

This  simple  precaution  readily  admits  of  the  easy  detachment  of  the 
cap  irom  the  model,  and  of  its  accurate  subsequent  replacement,  both  of 


303 

which  remove  any  difficulties  or  obstacles  incident  to  the  construction  and 
assemblage  of  the  parts,  and  to  the  subsequent  removal  and  investment  of 
the  piece ;  and  the  preservation  of  the  model  thus  made  possible,  affords 
opportunity  for  final  trials  at  any  time  during  or  after  the  completion  of 
the  case,  all  of  which  are  advantageous  features. 


ct 


Flcj. 


22a. 


When  the  model  has  been  separated  from  the  impression,  the  cap  may 
then  be  easily  removed  by  slightly  warming  the  surplus  end  of  the  dowel 
over  a  flame,  and  grasping  it  firmly  with  flat  beak  pliers,  wdien  a  straight 
pull  will  quickly  detach  it,  and  yet  leave  an  outline  of  such  accuracy  as  to 
admit  of  its  easy  and  correct  readjustment  to  position.     Fig.  225  A. 


I^icj.  225. 

After  thus  removing  the  cap  the  wax  should  be  burned  out,  and  it 
should  then  be  thoroughly  cleaned  in  the  acid  bath  to  insure  the  further 
removal  of  all  residue  from,  and  perfect  cleanliness  of,  the  metal,  when 
it  may  be  placed  upon  the  model,  or  laid  aside  for  the  time  l)cing,  if  prefer- 


304 

able,  and  the  wax  "bite"  adjusted  to  position,  Fig.  225  B,  and  the  case 
then  mounted  upon  the  articulator. 

When  more  than  one  crown  is  being  constructed  for  the  same  mouth 
at  the  same  time,  one  model  and  "bite"  is  all  that  is  necessary,  but  each 
individual  crown  should  always  be  separately  invested  and  soldered. 

While  the  ordinary  crown  ttrticulator  previously 
Tmproocd  illustrated  in  Fig.  71  may  be  used,  and  will,  of  course, 

JlrtiCUlators.  serve  the  purpose,  better  results   from  the  viewpoint 

of  a  more  accurate  articulation,  which  is  decidedly 
advantageous  particularly  when  porcelain  is  to  be  employed  in  any  man- 
ner, may  be  obtained  from  the  use  of  the  more  improved,  and  so-called 
anatomical,  articulators,  which  are  designed  more  especially  for  bridge- 
work,  and  which  admit  of  a  slight  forward,  backward  and  lateral  move- 
ment. 

Two  designs  possessing  these  features  which  seem  to  be  eminently 
practical  are  Kerr's  Improved  crown  and  bridge  articulator,  manufac- 
tured by  Mr.  M.  M.  Kerr,  of  Detroit,  Mich.,  and  the  design  manufactured 
by  the  Blue  Island  Specialty  Co.,  of  Blue  Island,  111.,  each  of  which  are 
simple  and  inexpensive. 


Principles  and  Cccbnique 
of  BridgeworR. 


filstory,  Development  ana  €tWc$  of  Dental  BridgeworK 


Chapter  XVII. 


The  art  of  dental  prosthesis,  and  particularly  in  so  far  as  it  pertains 
to  supplying  missing  teeth  by  attaching  artificial  substitutes  to  remaining 
natural  ones — which  is  now  termed  dental  bridgczcork — was  doubtless, 
and  is  recorded  as  being,  among  the  earliest  achievements  of  primitive 
dentistry. 

As  an  art  its  origin  has  been  traced  to  the  re- 
BiStOtV.  mote  epochs  of  the  Egyptians,  Phoenicians,  Greeks, 

Etruscans  and  Romans,  and  archeological  researches 
have  unearthed  specimens  which  give  silent  evidence,  and  prove  beyond 
peradventure,  that  the  possibilities  of  this  art  were  recognized  by  the 
people  of  these  ancient  periods ;  tliat  it  was  practiced  by  them  to  a  greater 
or  less  extent,  and  that  it  antedated  all  forms  of  plates  and  other  means 
of  supplying  missing  teeth. 

The  specimens,  especially  of  the  Etruscans — "thcje  wonderful 
fashioners  of  gold" — which  are  now  to  be  found  in  archeological  museums, 
bear  so  striking  a  resemblance  to  the  efforts,  even  of  the  present  time,  as 
to  cause  us  to  marvel  at  their  skill  and  ingenuity.  Several  comparatively 
excellent  pieces  of  work,  wherein  missing  teeth  were  substituted  by 
human  teeth,  or  by  those  of  lower  animals,  and  attached  to  remaining 
natural  ones  by  means  of  gold  wires  and  bands,  clearly  indicate  that  the 
Etruscan  dentists  were  not  only  skilful  in  the  manipulation  of  gold,  but 
also  that  they  were  familiar  with  a  variety  of  the  requirements  of  dental 
bridgework.     (Fig.  226.) 


3o8 

This  is  also  seen  in  the  efforts  of  the  Romans  who,  it  is  recorded, 
constructed  both  fixed  and  removable  appliances.  While  perhaps  not 
attaining  to  quite  so  high  a  degree  of  artistic  excellence,  they  neverthe- 
less show  their  familiarity  with  the  possibilities  and  requirements,  and 
exhibit  a  surprising  degree  of  mechanical  ingenuity. 


Fig.  226. 


Whether  or  not  such  efforts  became  a  lost  art  during  the  middle 
sges  is  of  course  not  known,  but  as  with  all  sciences  and  arts  it  is  pre- 
.sumed  to  have  at  least  suffered  a  period  of  marked  decline. 


Ficj.22  7. 


In  any  event  tlic  beginning  of  a  revival  of  these  ancient  methods  was 
not  marked  until  the  early  j)art  of  the  last  century,  and,  as  with  dentistry 
in  general,  and  dental  prosthetics  in  particular,  the  primary  evidences  of 
the  advent  of  its  evolution  doubtless  came  from  the  ]'>ench. 

While  a  few  crude  reports  of  isolated  cases  preceded  it,  the  first 
presentation  of  methods  for  thus  supplying  missing  teeth  was  probably 


309 

made  by  F.  Maury  in  a  work  entitled  "A  Treatise  on  Dental  Art,"  pub- 
lished in  the  French  in  1828,  and  translated  by  J.  B.  Savier  in  1843. 
Among  several  illustrations  of  methods  of  supplying  artificial  teeth  which 
are  to  be  found  in  this  early  work,  are  at  least  hi'o  wherein  remaining 
teeth,  or  roots,  afford  the  sole  means  of  attachment  for  the  substitutes, 
without  any  apparent  effort  to  secure  stability  by  resting  or  impinging 
to  any  extent  upon  the  adjacent  soft  tissues.     (Fig.  22"].^ 


Fiq.  228. 


The  substitutes  used  at  that  time  were  largely  those  which  had  been 
carved  from  the  "sea-horse"  tooth,  though  the  use  of  the  crowds  of  human 
teeth  so  modified  as  to  meet  the  requirements,  is  mentioned,  and  in  some 
places  occur  descriptions  of  porcelain — or,  as  they  were  then  called,  incor- 
ruptible— teeth. 

That  which  has  been  termed  the  "progenitor  of 

Development,  modern  bridgework"   is   recognized   as   having  been 

first  suggested  by  Dr.  VV.  A.  Dwindle  in  1856,  when  a 

description  of  a  method  of  adapting  a  plate  to  the  end  of  the  root  and 


'-'     F/cj.229. 

attaching  an  artificial  tooth  to  it,  was  further  supplemented  by  the  state- 
ment that  "the  plate  may  be  carried  across  an  intervening  space  unoccu- 
pied by  roots  and  an  unbroken  row  of  teeth  mounted  upon  it." 

However  original  this  idea  may  or  may  not  have  been,  it  nevertheless 
sounded  the  tocsin  for  a  revival  of  the  methods  of  greater  or  less  antiquity 


3IO 

and  marked  the  beginning  of  an  era  of  development  which  has  resulted  in 
the  methods  of  Ijday,  and  which  development  also  must  redound  to  the 
credit  of  American  dentistry. 

In  1 8/ 1  Dr.  B.  J.  Bing  contributed  largely  to  this  development  by 
devising  an  artificial  tooth  made  of  porcelain,  and  having  a  platinum  bar 
projecting  from  each  lateral  side,  the  ends  of  which  were  to  be  anchored 
in  fillings  in  the  adjacent  natural  teeth.  (Fig.  228.)  This  became  known 
as  the  "Bing  bridge,"  and,  while  applicable  only  to  the  replacement  of  a 
single  tooth,  its  introduction  nevertheless  marked  the  advent  of  the  mod- 
ern application  of  fixed  bridgework,  for  which  its  designer  must  be 
accorded  the  credit. 

Shortly  after  this,  in  1873,  that  great  American  genius.  Dr.  W.  G.  A. 
Bonwill,  devised  and  presented  a  type  of  removable  bridge  wherein  a  metal 
tube,  previously  threaded  on  its  inner  surface,  was  mounted  in  the  root 
canal,  and  used  as  a  means  of  afifording  attachment  for  a  removable  crown. 
The  crown  was  adapted  to  the  root  and  sustained  in  position  by  a  threaded 
dowel  which  passed  through  a  perforation  in  its  base  and  engaged  with 
the  tube,  and  was  capable  of  carrying  one  adjacent  tooth  when  provided 
with  a  means  of  preventing  rotation.     (Fig.  229.) 


r/Q.230. 


Those  devices  of  mechanical  and  artistic  ingenuity,  however,  which 
may  now  be  classified  as  modern  dental  bridgework,  had  their  beginning 
with  the  advent  of  the  gold  shell  or  telescope,  and  the  band  and  dowel 
crowns ;  and  hence,  the  practical  application  of  this  class  of  work,  on 
modern  lines,  dates  back  only  to  the  period  between  1878  and  1883,  when 
the  usefulness  of  these  styles  of  crowns  first  became  recognized. 

Since  this  time  the  development  of  methods  involving  various  prin- 
ciples has  been  so  rapid  as  to  preclude  further  enumeration  of  any  except 
those  the  application  of  which  is  regarded  as  being  practicable  at  the 
present  time. 


311 

Before  entering  upon  a  description  of  any  of  the 
€tblc$.  various  methods  of  procedure  now  employed,  how- 

ever, there  are  certain  fundamental  considerations  of 
sufficient  importance  to  demand  special  emphasis ;  not  the  least  among 
which  is  that  of  ethics. 

The  many  objectionable  features  incident  to  the  wearing  of  "plates" 
and  other  forms  of  artificial  denture.s  which  derive  their  stability  from  im- 
pingment  upon  the  soft  tissues  of  the  mouth,  has  caused  the  profession  to 
be  so  deluged  with  a  multitude  of  devices  for  overcoming  such  objections 
as,  almost  of  necessity,  to  result  in  many  of  them  proving  absolute  failures 
when  subjected  to  the  test  of  practicability.  Hence  the  application  of 
dental  bridgework,  even  of  the  more  modern  forms  of  construction,  like 
almost  every  other  human  effort,  has  been  subject  to  both  use  and  abuse, 
and  has  been  productive  of  both  good  and  evil. 


F/cj.  23L 


As  any  art  must  undergo  its  experimental  stages,  however,  overen- 
thusiastic  and  perhaps  even  indiscriminate  application  could  not  be  well 
avoided,  and  such  failures  as  must  result  therefrom  should  bv  no  means 
provoke  irrevocable  condemnation.  On  the  contrary,  since  it  is  by  our 
failures  that  we  learn  and  profit  most,  many  of  them  were  only  a  logical 
sequence,  and  have  been  but  steppingstones  to  the  gradual  process  of 
development. 


312 

That  a  large  proportion  of  the  early  efforts  in  this  direction  were  not 
highly  successful  must  be  conceded,  but  many  of  them  were  failures  xiot 
so  much  because  the  underlying  principles  were  wrong,  but  largely  be- 
cause of  failure  to  properly  observe  them.  Yet  a  proper  observation  of 
such  principles  could  not  well  obtain  until  they  became  definitely  known, 
and  they  could  not  become  known  except  through  experience. 

A  typical  case  of  absolute  ignorance  of,  or  indifference  to,  the  under- 
lying principles  and  mechanical  requirements,  is  shown  in  Fig.  230,  where 
a  cap  without  a  dowel  and  two  partial  crowns  were  expected  to  support, 
and  thus  do  the  work  of  eight  or  nine  teeth.  The  application  of  such  de- 
vices could  only  invite  and  result  in  failure  of  the  most  pronounced  type, 
but  fortunately  would  usually  do  but  little  injury  to  the  abutment  teeth 
because  of  possessing  so  limited  a  degree  of  permanency. 

It  is  true,  however,  that  much  unnecessary  evil 

€\Jil  effects.  has  occurred,  but  the  greatest  proportion  of  such  re- 

sults can  undoubtedly  be  traced  directly  to  the  degree 
of  over-enthusiasm,  and  pecuniary  greed,  which  has  induced  an  injudicious 
and  indiscriminate  application  at  the  hands  of  uneducated,  unskilful  and 
unscrupulous  operators. 

Such  lamentable  efforts  as  these  usually  come  from  the  hands  of  those 
who  conduct  the  so-called  "dental  parlors"  and  make  "teeth  without 
plates;"  where  many  teeth  are  crowned  which  should  and  would  other- 
wise be  filled ;  where  the  application  of  a  glaring  gold  crown  on  any  tooth, 
or  bridges  like  those  illustrated  in  Fig.  231,  is  but  the  work  of  a  few  mo- 
ments ;  and  where  the  salvation  of  a  tooth,  the  development  of  an  art,  and 
the  honor  of  a  useful  profession  is  sacrificed  on  the  altar  of  Mammon. 

In  the  "bridges"  illustrated  the  one  designated  "A"  shows  where 
five  teeth  are  attached  to  two  gold  crowns  adjusted  to  teeth  which  have 
received  no  preparation  whatever ;  "B"  shows  the  two  laterals  suspended 
by  three  simple  bands,  also  similarly  adjusted,  and  "C"  shows  a  most 
flagrantly  impracticable  specimen  of  so-called  "alveolan  dentistry." 
While  the  former  case  was  doubtless  capable  of  affording  some  degree  of 
permanency,  yet  it  would  indeed  be  difficult  to  conceive  of  anything  more 
inartistic;  and  the  latter  cases  (B  and  C),  while  almost  equally  inartistic, 
could  only  result  in  the  early  disintegration  or  loss  of  the  teeth  thus 
banded. 

Indeed,  alx:ive  all  others,  the  one  practice  which  has  done  more  to 
retard  the  develoi)mcnt  of  this  art  al(jng  ])ractical  and  mechanical  lines, 
and  which  has  been  productive  of  a  most  Ijaneful  influence  upon  support- 
ing teeth,  has  been  that  (jf  the  indiscriminate  and  pernicious  use  of  simple 
bands  for  supporting  missing  teeth. 


313 

This  utter  disregard  for  the  laws  of  mechanics  and  hygiene,  and  for 
the  requirements  of  art  and  esthetics  which  successful  application  of  this 
art  demands,  has  undoubtedly  resulted  in  a  class  of  work  which  could  only 
prove  to  he  a  positive  source  of  injury  to  the  teeth  and  health  of  the 
victim,  and  which  could  also  but  invite  the  premature  loss  of  a  multitude 
of  good  sound  teeth,  and  much  attending  discomfiture,  and  discourage- 
ment. 

Notwithstanding  these  flagrant  evidences  of  commercial  dentistry, 
the  development  of  this  art  in  the  past  decade  has  placed  it  upon  a  sound 
scientific  and  practical  basis  ;  and  if  its  application  be  so  governed,  and 
conscientiously  made,  there  should  be  no  reasonable  excuse  for  the  loss 
of  teeth,  or  for  failures. 

The  real  benefit  which  has  been  derived  by  both 

600d  effects.  the  profession  and  the  laity   from  a  judicious  and 

skilful  application  is  beyond  comprehension  or  con- 
tradiction. As  pertains  to  the  profession,  the  advent  of  bridgework  has 
been  the  means  of  affording  a  training  in  artistic  and  mechanical  technique 
unequaled  by  any  other  phase  of  dentistry,  and  the  possibilities,  which 
were  early  recognized,  have  served  as  a  constant  stimulus  to  the  inventive 
genius  of  its  members. 

It  has  served  to  make  the  operator  a  better  mechanic,  and  consequently 
in  turn  a  better  operator,  and  also  to  increase  his  artistic  attainments  and 
thus  make  him  a  better  dentist.  Unlike  the  advent  of  vulcanite  work,  it 
has  brought  the  two  departments  of  practical  dentistry  into  closer  rela- 
tionship, and  has  elevated  the  art  of  dental  prosthesis  beyond  the  sphere 
of  mere  laboratory  mechanics. 

In  so  far  as  benefits  to  the  laity  is  concerned  there  can  be  no  doubt 
but  that  a  well-planned,  skillfully  executed  and  properly  adjusted  bridge, 
when  indicated,  wmII  contribute  much  to  the  comfort  and  health  of  the 
patient  who  is  thus  disfigured  by  the  premature  loss  of  natural  teeth. 

To  obtain  these  desirable  results  in  a  large  proportion  of  cases  has 
been  made  possible  by  the  development  of  this  art,  but  their  achievement 
demands  a  broad  and  liberal  knowledge  of  the  requirements ;  underlying 
principles  and  limitations,  and  a  thorough  and  conscientious  execution  of 
the  details. 

In  this  connection  it  must  be  remembered  that  the  conditions  with 
which  we  meet  vary  to  a  greater  or  less  extent  with  each  individual  case, 
and  that  no  mechanical  device  which  is  designed  to  become  a  part  of  the 
human  economy  is  capable  of  universal  application. 

Hence  it  is  the  duty  of  the  conscientious  operator  to  study  each  case 
presenting  with  a  view  to  accomplishing,  not  in  the  most  simple  or  ex- 


314 


peditious  manner,  but  in  the  best  and  most  favorable  manner  those  results 
which  in  his  judgment  will  seem  to  offer  the  very  highest  possibilities  from 
the  combined  viewpoints  of  simulating  nature  and  restoring  lost  function. 
If  he  be  not  qualified  to  do  this,  or  is  unwilling  to  do  it  conscien- 
tiously, he  has  no  right  to  inflict  unskilful  or  indifferent  services  upon  a 
confiding  patron.* 


*An  acknowledgment  of  indebtedness  for  some  of  the  references  made  and  illustrations 
used  in  this  chapter,  is  hereby  made  to  Dr.  Vincenzo  Guerini,  of  Naples,  Italy  (Dental  Cosmos, 
January,  1901);  Or.  M.  L.  Rhein  (Dental  Cosmos,  February,  1894),  and  to  the  "American 
System  of  Prosthetic  Dentistry,"  and  Evans'   "Crown  and  Bridgcwork." 


e;i<)$$ificdtion,  Principles  ana  Requirements  of  Dental  Briddework. 


CHAPTER  XVIII. 

Classification:     Abutments;  Attachments  or  Abutment  Pieces;  Dummies.    Remov- 
able  Bridgework.     Fixed  Bridgework :      Extension  Bridges,   Saddle  Bridges, 
Interrupted    Bridges.       Advantages   and    Disadvantages   of   Bridgework. 
Principles:    Application    to    Fixed   Bridgework.      Application   to    Re- 
movable  Bridgework.     Requirements:  Physiological;  Abutments, 
Devitalization    of    Pulp,    Hygienic    Considerations :     Physio- 
Chemical  Aspect,  Mechanical  Preparation  of  Abutments, 
Adaptation   of   Attachments,    Construction;    Contact, 
Articulation  and  Occlusion,  Assemblage.  Esthetic. 


The  practice  of  no  phase  of  the  science  or  art  of  dentistry  reqtiires 
the  exercise  of  so  great  a  degree  of  mechanical  iiigciuiify,  jiiaiiipiilatk'e 
ability,  artistic  attaiiiment,  and  good  sound  judgment  as  is  demanded  in 
the  successful  apphcation  of  dental  bridgework.  Whenever  the  applica- 
tion may  be  made  along  these  lines,  however,  or  in  consonance  therewith, 
there  is  also  no  phase  of  dental  art  which  offers  greater  possibilities,  or 
greater  opportunities  for  successful  achievements.  Furthermore,  the  suc- 
cess which  may  be  thus  attained  contributes  as  much  to  the  appearance, 
comfort  and  health  of  the  patient  as  it  does  to  the  satisfaction  of  even 
the  most  conscientious  and  ambitious  practitioner. 

Cldssificatiott. 

Technically,  dental  bridgework  constitutes  an  assemblage  of  attach- 
moits  or  abutinoit  pieces,  and  intervening  or  adjacent  duinniies,  which, 
when  united,  afford  a  continuous  incisal  or  masticating  stirface. 

The  principles  underlying  the  mechanical  means  of  supporting  the 
work  are  derived  mainly  through  attachment  to  the  natural  teeth,  and 
while  the  intervening  teeth  are  usually  placed  in  direct  contact  ^vith  the 
contiguous  soft  tissues,  any  support  which   is  afforded  by,   or  obtained 


3i6 

from,  such  impingement  is  necessarily  supplementary,  and  consequently 
becomes  a  secondary  consideration. 

The  anchorage  may  be  secured  eithei  upon  the 

JlbUtmentS.  roots,  or  to,  or  in  the  crowns  of  the  natural  teeth, 

and  the  teeth  thus  used  are  known  as  "abutments." 

The  methods  of  anchorage  to  the  natural  teeth 

..  ™  !!!.        ..     which  are  employed  mav  be,  and  are,  designated  as 

''Jftutment  Pieces."      ,,    ,       .....  ^ 

attachments  or    abutment  pieces. 

The  artificial  substitutes  for  the  missing  natural 
Dummies.  teeth,  which  are  supplied  by,  and  which  form  the  body 

of  the  bridge  are  commonly  known  as  "dummies." 
When  the  attachments  or  "abutment  pieces"  and  "dummies"  are  as- 
sembled they  constitute  a  mechanical  device,  which,  "like  a  continuous 
chain,  can  be  no  stronger  than  its  weakest  link,"  and  which  in  its  attach- 
ment can  possess  no  greater  degree  of  strength  than  is  afforded  by  the 
stability  of  the  supporting  teeth.  Hence,  the  practicability  of  the  piece 
will  depend,  first,  upon  the  stability  of  the  abutments,  and,  second,  upon 
the  manner  in  which  it  is  planned  and  constructed. 

Irrespective  of  the  many  variations  of  construction,  the  application 
involves  but  tzvo  general  lines  of  procedure.  These  may  be  classified  as 
removable,  and  fixed  or  "stationary"  bridgework. 

Removable  bridgework   embraces  that  style  of 
KemOPable  construction  wherein  an  impingement  of  the  body  of 

Btldsework.  the  piece  upon  the  contiguous  soft  tissues  is  supple- 

mented by  some  form  of  attachment  to  the  abut- 
ment which  affords  temporary  fixation  and  stability  when  in  position,  and 
vet  admits  of  the  ready  removal  and  replacement  without  disturbing  the 
integrity  of  any  of  the  parts. 

That  type  of  construction  which  is  designed  to 
Tlxed  Bridflework,       l^^  securely  and  permanently  anchored  to  the  abut- 
ments in  such  manner  as  to  preclude  its  removal  with- 
out the  mutilation  of  the  attachments,  thus  becoming  a  fixed  or  integral 
part  of  the  denture,  is  designated  as  "fixed"  bridgework. 

That  style  of  construction  wherein  the  possible 
extension  stability  of  the  abutments  admits  of  extending  one 

Bridges.  or  two  teeth  either  posterior  or  anterior  to  an  attach- 

ment, without  any  additional  support  except  that 
afforded  by  impingement  up(jn  the  soft  tissues,  is  designated  as  "exten- 
sion" bridges.  While  usually  applied  with  special  reference  to  "fixed" 
appliances  the  principle  is  nevertheless,  of  course,  likewise  applicable  to 
"removable"  ones. 


JI7 

The  term  "saddle  bridges"  is  applied  to  that  type 
Saddle  Bridges.  of  construction  wherein  the  body  of  the  bridge  is  con- 

formed to  the  outline  of,  and  placed  in  contact  with, 
the  gum  tissue.  The  designation  mainly  applies  and  refers  to  "fixed" 
bridgework,  for  the  reason  that  all  removable  appliances  are  so  con- 
structed. 

The  term  "interrupted"  bridge  is  applied  to  that 

TntcrruptCd  type  of  construction  in  which  the  presence  of  a  re- 

BridgCS.  maining  natural  tooth  not  required  as  a)i  abutment 

may  cause  an  interruption  in  the  continuous  relation 

of  the  parts.     The  relation  of  the  various  parts  to  each  other  and  the 

integrity  of  the  bridge,  however,  is  sustained  by  the  use  of  a  heavy  bar 

of  platinum,  iridio-platinum,  or  gold,  adjusted  to  conform,  approximately, 

with  the  outline  of  the  lingual  surface  of  the  remaining  tooth,  without 

resting  upon  it,  impinging  upon  the  soft  tissue,  or  interfering  with  the 

occlusion.     This  principle  is  also  applicable  mainly   to   "fixed"   bridges, 

though  technically  it  may,  of  course,  be  likewise  applied  to  those  which 

are  removable. 

Mumm  ^nd  Disadvantddes  of  Briddcwork. 

The  application  of  dental  bridgework,  of  either  of  the  two  general 
types  of  construction  which  have  been  designated  as  "fixed"  or  "remov- 
able" in  character,  presents  phases  of  advantages  and  disadvantages 
which,  while  being  mainly  applicable  to  the  former  class,  are  nevertheless 
also  more  or  less  applicable  to  the  latter  class,  though  always  in  a  more 
modified  form. 

The  advantages  generally  claimed  may  be  enu- 

fldPantagcs.  merated  as  follows  : 

I.  The  removal  of  the  many  deficiencies  asso- 
ciated with  the  substitution  of  missing  natural  teeth  by  means  of  the  more 
common  forms  of  plates  which  depend  entirely  upon  contact  for  retention. 

2.  The  overcoming  of  the  more  or  less  embarrassing  features  coinci- 
dent with  the  wearing  of  artificial  teeth  supplied  by  such  means  of 
retention. 

3.  The  avoidance  of  any  mechanical  abrasion  of  the  remaining  natural 
teeth  from  clasps,  or  contact  of  plate,  and  the  preservation  of  their  integ- 
rity, and  of  the  normal  condition  of  the  contiguous  tissues,  thus  over- 
coming any  possible  tendency  to  looseness  and  subsequent  loss  which  mav 
result  from  such  contact. 

4.  The  removal  of  the  impediment  to  speech,  taste,  etc.,  which  is 
usually  caused  by  plates. 


3i8 

5.  The  more  perfect  reproduction  of  masticating  surfaces  which  is 
aflforded  by  the  firmness  and  immobihty  derived  from  a  more  Used  type  of 
construction. 

The   disadvantages   incident   to  the   substitution 
Disadvantages.  of  lost  teeth  by  means  of  bridgevvork  are  summarized 

as  follows : 

1.  The  possible  necessity  for  the  devitalization  of  the  pulp,  and 
the  mutilation  of  perhaps  sound  teeth,  which  must  necessarily  be  em- 
ployed as  abutments. 

2.  The  unnatural  condition  established  by  the  secure  fixation  of  the 
roots  of  two  or  more  teeth. 

3.  The  additional  stress  to  which  the  abutments  are  necessarily  sub- 
jected. 

4.  The  progressive  degeneration  of  the  peridental  membrane  which 
mav  thus  possibly  ensue,  cause  looseness,  and  result  in  subsequent  loss  of 
teeth. 

5.  The  unhygienic  and  consequently  unhealthy  condition  which  may 
be  induced  by  the  wearing,  particularly,  of  extensive  "fixed"  bridges. 

An  analysis  of  the  possible  advantages  and  disadvantages  as  thus 
enumerated  would  seem  to  leave  some  degree  of  doubt  as  to  the  general 
practicability  or  impracticability  of  this  class  of  work.  Clinical  experi- 
ence has  proven,  however,  that  if  the  application  be  judiciously  made,  and 
made  in  accordance  with  a  knowledge  and  observation  of  the  underlying 
fundamental  principles,  and  the  physiological  and  mechanical  require- 
ments, the  possible  unfavorable  conditions  may  be  minimized,  and  the  op- 
portunities for  obtaining  the  more  favorable  ones  be  correspondingly 
enhanced. 

As  these  considerations  apply  to  bridgework  in  general,  the  particu- 
lar advantages  and  disadvantages  incident  to  the  judicious  application  of 
each  respective  type  of  construction,  and  the  indications  and  contra-indica- 
tions  for  same,  will  first  be  generally  considered  under  the  caption  of  prin- 
ciples, and  then  subsequently  further  discussed  in  connection  with  the 
presentation  of  methods  of  construction. 

Principles, 

In  a  previous  consideration  of  this  subject,  it  has  been  correctly  stated 
that  the  application  of  dental  bridgework  involves  "a  multitude  of  devices 
which  depend  upon  a  few  limited  mechanical  principles" ;  and  yet,  how- 
ever few  may  be  involved,  a  knowledge  of  the  fundamental  principles 
underlying  the  application  of  any  mechanical  pursuit  is  always  to  be  con- 
sidered as  a  prerequisite  to  successful  achievement,  and  particularly  so 


319 

when  these  principles  are  to  be  appHed  to  structures  attached  to  the 
human  body. 

In  the  procedure  incident  to  devising  and  constructing  dental  bridges, 
the  first  and  most  important  considerations  presenting  are  obviously  those 
of  the  stability  of  the  teeth,  which  are  to  serve  as  abutments,  and  the 
reqiiirciiiciifs  of  occlusion,  which,  as  viewed  from  a  mechanical  aspect,  are 
co-incident  with  the  physical  considerations  of  stress  and  resistance. 

Irrespective  of  the  innumerable  variety  of  methods  of  attachment 
which  are  employed,  the  general  principles  underlying  the  application  of 
this  work  apply,  fundamentally  at  least,  to  any  style  of  construction, 
though  always  with  somewhat  less  force  to  those  which  are  designed  to  be 
"removable"  in  character  than  to  that  style  which  is  intended  to  become 
a  "fixed"  part  of  the  denture. 

In  either  class  of  construction,  in  proportion  as  the  stress  imposed 
upon,  or  to  be  assumed  by  the  abutments  is  diminished,  the  number  of 
"dummies"  which  they  may  be  reasonably  expected  to  support  of  course 
increases ;  and,  irrespective  of  the  method  of  anchorage,  the  degree  of 
stress  to  which  the  abutments  must  be  subjected  will  depend  largely  upon 
the  number  of  remaining  natural  teeth  not  included  in  the  bridge,  and  will 
decrease  in  proportion  to  the  degree  to  which  the  normal  occlusal  relations 
may  be  restored. 

Thus  the  presence  or  absence  of  occluding  natural  teeth  will  so  affect 
or  relieve  the  abutments  as  to  govern  the  indications,  to  a  large  extent,  for 
each  respective  type  of  construction,  and  to  bear  materially  upon  the  prac- 
ticability or  impracticability  of  either. 

Hence  these  physical  and  mechanical  considerations  demand  that  the 
construction  of  dental  bridges  be  based  largely,  if  not  exclusively,  upon 
the  conditions  and  the  requirements  of  each  case ;  and  those  are  usually 
so  diversified  in  range  as  to  preclude  the  universal  application  of  any  one 
general  line  of  procedure. 

Jlpplication  to  **Tixed"  Bridgcwork, 

As  related  particularly  to  the  application  and  construction  of  "fixed" 
bridges,  the  root  of  almost  any  tooth  in  the  arch  is  so  cushioned  and  pro- 
tected by  nature  as  to  render  it  capable  of  withstanding  xwtical  stress  to 
a  degree  exceeding  its  own  individual  requirements  ;  hence  it  may  be  gen- 
erally accepted  as  a  cardinal  principle  that  one  tooth  is  capable  of  perform- 
ing the  function  of  tzi'o — under  favorable  conditions.  Since  a  similar  pro- 
tection against  lateral  stress,  however,  is  not  atiforded  by  the  nature  of  the 
surrounding  tissues,  all  roots,  and  particularly  those  of  conical  shape,  will 
yield  more  or  less  readily  whenever  in  any  manner  subjected  thereto.    For 


320 

this  reason  the  provision,  under  favorable  conditio)is,  means  much  as 
regards  the  appHcation  of  the  principle,  and  the  practicability  of  the  work 
constructed  in  accordance  with  it.  It  means,  first  of  all,  that  the  physio- 
logical condition  of  the  tooth,  and  of  its  surrounding  tissues,  must  be 
favorable;  and,  second,  that  the  mechanical  demands  imposed  upon  it 
must  be  within  the  limits  of  its  endurance. 

An  observation  of  the  combined  physical  and  mechanical  require- 
ments thus  imposed  would  demand,  first,  that  the  tooth  to  be  so  utilized 
must  possess  a  degree  of  inherent  stability  equal  to  or  greater  than  that  re- 
quired of  the  substitute  which  it  is  to  support ;  and  second,  that  a  means 
of  fortifying  it  against  leverage  or  rotation  on  its  long  axis,  or  against  the 
possibility  of  a;;y  lateral  movement,  must  be  provided. 

Thus,  from  a  physical  viewpoint,  it  is  apparent  that  it  would  not  be 
practicable  to  expect  a  lateral  incisor  to  support  a  central  incisor,  or  a 
cuspid ;  nor  a  second  bicuspid  to  support  a  first  molar,  because  the  natural 
requirements  occasioned  by  the  proportions  of  the  root,  or  the  location  in 
the  arch,  of  the  tooth  so  supported  exceed  those  of  the  abutment  or  sup- 
porting tooth. 

Reversing  these  conditions,  however,  it  would  be  reasonable  to  ex- 
pect a  central  incisor,  or  a  cuspid,  to  support  a  lateral  incisor ;  a  first 
bicuspid  to  support  a  cuspid ;  a  second  bicuspid  to  support  a  first  bicuspid, 
or  a  first  bicuspid  to  support  a  second  bicuspid,  and  a  first  molar  to  support 
a  second  bicuspid,  because  in  these  instances  the  inherent  physical  stability 
and  natural  requirements  of  the  abutment  or  supporting  tooth  exceed  or 
equal  those  of  the  tooth  which  is  thus  supported.  Likewise,  a  central  in- 
cisor will  support  the  adjacent  central,  because  in  this  particular  instance 
the  abutment  or  supporting  tooth  possesses  a  degree  of  stability  equal  to 
the  requirements  of  the  supported  tooth. 

This  general  principle,  however,  applies  only  to  one  end  of  even  the 
most  simple  bridges,  and,  as  a  rule,  its  practicability  will  demand  that  the 
other  end  be  adequately  protected  against  the  leverage  produced  by  lateral 
or  even  vertical  stress,  as  previously  mentioned.  An  exception  to  this 
latter  requirement,  however,  as  applied  to  the  first  molar,  may  sometimes 
be  made,  as  this  particular  tooth,  owing  to  its  relative  proportions  and 
position  in  the  arch,  will  usually  support  a  second  bicuspid  without  such  a 
provision. 

As  pertains  to  a  more  extensive  application  of  general  principles  to 
typical  cases,  the  following  may  be  generally  accepted  as  being  practicable, 
if  it  be  generally  understood  an<l  appreciated,  first,  that  by  uniting  two 
teeth  they  act  as  one,  capable  of  withstanding  a  minimum  stress  of  two ; 
second,  that  there  can  be  no  movement  of  the  piece  independent  of  the 


321 

abutments  themselves,  and  third,  that  the  stabiHty  of  the  piece  will  de- 
pend upon  the  strcngtli  and  position  of  the  abutments,  and  the  security 
of  the  attachment  to  them. 


/^icj.232. 


The  two  central  incisors  will   support  the  two 
type  TK,  lateral  incisors,  and  often  if  the  roots  are  of  good 

proportion  and  in  reasonably  good  condition,  the  two 
laterals  will  in  turn  support  the  two  centrals.     (Fig.  232,  A  and  B.) 

The  two  cuspids  will  usually  possess   sufficient 

type  B.  stability  to   support  the   four  incisors.      (Fig.   233.) 

This  principle  is  always  applicable  to  the  lower  arch. 


Fiq.  233. 

but  as  applied  to  the  upper  arch  the  degree  of  practicability  will  depend 
largely  upon  the  occlusion,  and  will  increase  in  proportion  as  the  length 
of  the  overbite  may  be  shortened.     (Fig.  234,  A.) 


322 

Thus,  if  the  occlusion  may  be  made  so  as  to  have  the  incisal  ends  of 
the  upper  teeth  come  in  direct  contact  with  the  incisal  ends  of  the  lower 
teeth— which  is  commonly  designated  as  an  "end  to  end"  bite  (Fig. 
234,  B) — or  as  nearly  so  as  possible — the  degree  of  lateral  stress  is  di- 


/7^.234. 


minished,  and  the  stress  thus  becoming  more  nearly  vertical,  which  is  in 
line  with  the  greatest  resistance,  makes  the  application  more  favorable, 
and  precludes  the  possibility  of  the  cuspids  being  forced  forward,  or  out- 
ward and  upward,  ultimately  producing  a  separation  between  them  and 
the  first  bicuspids. 


F/(^.  235. 


This  displacement  will  almost  invariably  result  when  considerable 
"overbite"  exists,  th(nigh  tin-  ])rcsence  or  absence  of  the  posterior  teeth, 
anrl  the  accuracy  of  their  occlusion,  will  have  a  marked  bearing  upon 
this   tendency   to   subsequent   protrusion,    because   their   presence   would 


323 

naturally  relieve  the  anterior  teeth  of  much  stress,  which  an  interrupted 
occlusion  produced  by  their  absence  would  occasion. 

Such  a  tendency  or  possibility,  in  this  connec- 
CypC  €.  tion,  would  practically  be  entirely  overcome  by  the 

presence  and  use  of  an  intervening  central  or  lateral, 
because  of  the  increased  resistance  thus  afforded.     (Fig.  235.) 


type  D. 


Ficf.236. 

As  a  good  tooth  on  each  end  will  always  support 
two  intervening  teeth  in  any  application,  the  cuspid 
and  first  molar  will,  of  course,  support  the  two  bicus- 


Fiq.237, 

pids  (Fig.  236,  A),  or  the  two  bicuspids  and  lateral.  (Fig.  236.  B.) 
Either  one  of  these  applications  is  typically  practical,  because  of  the 
maximum  degree  of  stability  obtained  from  the  use  of  these  particular 
teeth  as  abutments. 


324 

The  second  bicuspid  and  second  molar  will  sup- 
Zypi  €.  poi't  the  first  molar  and  first  bicuspid  without  any 

additional  anchorage  anterior  to  the  latter.  (Fig. 
237,  A.)  In  this  construction,  however,  it  is  not  usually  desirable  or 
necessary  to  have  the  first  bicuspid  "dummy"  possess  an  appreciable  oc- 
clusal surface,  for  the  reason  that  this  particular  tooth  is  seldom  required 
to  do  much  masticatory  zi'ork,  and  the  strength  of  the  bridge  will  be 
increased  by  throwing  the  actual  work  upon  the  three  teeth  posterior  to 
it,  two  of  which  are  abutments. 


F/q.Z38. 


As   a  general  rule,   the  first  bicuspid  and  first 
type  T.  molar  might  be  expected  to  support  the  second  bicus- 

pid and  second  molar,  without  any  additional  anchor- 
age at  the  posterior  end.  (Fig.  237,  B.)  In  this  construction,  however, 
while  the  presence  and  use  of  the  third  molar  may  not  be  necessary,  be- 
cause of  the  stability  of  the  first  molar,  still  its  employment  would,  of 
course,  add  strength  to  the  fixation  of  the  work,  and  appreciably  relieve 
both  of  the  other  abutments.  As  the  third  molar  and  first  molar,  how- 
ever, would  also  support  the  missing  second  molar  and  second  bicuspid, 
it  would  always  be  best  to  use  them,  and  tlms  avoid  employing  the  first 
bicuspid  at  all. 

While  the  cuspid  and  second  molar  will  usually 

tyyc  6.  support   ilic   tlircc   intervening  teeth    (Fig.   238,  A), 

tlic  same  degree  of  success  and  permanency  offered 

in  this  application  is  not  usually  to  be  obtained  wliere  the  third  molar  is 

used  as  the  posterior  aljutment,  and  four  intervening  teeth  are  supplied. 

(Fig.  238,  B.) 


325 

In  the  event  of  the  forward  gravitation  of  this  tooth,  however,  to  an 
extent  which  will  onl}-  require,  or  admit  of,  three  intervening  dummies, 
the  use  of  the  third  molar  is,  of  course,  more  practicable,  and  increases  in 
proportion  to  its  size  and  stability. 

The  two  cuspids  and  the  first  molar  on  one  side 

type  R.  will  usually  support  the  intervening  four  incisors  and 

two  bicuspids    (Fig.   239,   A),   and   while  the  three 

teeth  will  thus  be  required  to  do  the  work  of  nine,  such  a  structure  is 

nevertheless  practicable,  if  the  occlusion  and  stability  of  the  abutments 

are  favorable. 


F/^,  239. 


The  two  cuspids  and  two  first  molars  will  also  usually  support  the 
entire  denture  anterior  to  the  latter  teeth  (Fig.  239,  B).  Where  other 
than  the  first  molars  can  and  must  be  used,  however,  the  stability  of  the 
abutments  is  lessened,  while  the  requirements  are  increased,  and  conse- 
quently the  degree  of  practicability  is  not  so  great. 

Throughout  the  construction  of  this  work,  by  far  the  largest  propor- 
tion of  success  will  be  derived  from  the  use  of  small  bridges,  and  the 
opportunities  for  achieving  these  desirable  results  will  usually  be  lessetied 
as  the  operation  becomes  more  extensive,  or  as  the  number  of  teeth 
involved  increases. 

Supplementary  principles  which  will  materially  add  to  the  opportuni- 
ties, and  which  must  always  be  observed  if  success  is  to  be  attained,  are 
herewith   indicated : 

I.  Do  not  attempt  extensive  operations  with  a  view  of  obtaining 
more  or  less  permanent  results  in  the  mouths  of  patients  under  fourteen 
or  fifteen  years  of  age,  as  the  conditions  are  usually  ver_\-  unfavorable  at 
this  time. 


326 

2.  Do  not  use  loosened  and  unhealthy  roots  for  abutments,  as  such 
conditions  only  invite  failure. 

3.  Always  increase  the  resistance  and  lessen  any  possible  chance  of 
failure  hv  utilizing  a  lua.viiiiuiii  instead  of  a  minhnum  number  of  abut- 
ments, 

4.  Always  make  every  possible  mechanical  provision  against  the  in- 
fluences of  lateral  or  antero-posterior  stress. 

5.  Always  avoid  an  interlocking  occlusion  or  an  unfavorable  articu- 
lation, which  will  in  any  manner  interfere  with  or  prevent  the  free  lateral 
movement  of  the  mandible  in  the  act  of  mastication. 

6.  Have  the  occlusion  of  the  abutments,  if  anything,  more  deiinite 
than  that  of  the  "dummies,"  whenever  possible,  and  provide  the  latter  with 
as  small  an  occlusal  surface  as  is  consistent  with  the  requirements  of 
mastication,  thus  minimizing  the  stress  to  be  endured  by  them. 

Jfppllcatlon  to  **Kcmov)aWc"  BridgcworR. 

While  these  same  general  principles  apply  also  to  "removable"  de- 
vices, yet  the  advantages  obtained  from  the  support  derived  from  impinge- 
ment upon  the  soft  tissues,  together  with  the  slight  degree  of  mobility 
which  the  attachments  for  this  class  of  work  usually  afford,  imposes  less 
actual  stress  upon  the  abutments.  Hence,  in  proportion  as  the  stress  im- 
posed upon,  or  the  work  required  of  the  abutments  is  diminished,  the 
number  of  teeth  which  they  may  be  reasonably  expected  to  support 
increases. 

The  successful  application  of  dental  bridgework  is  based  so  largely 
upon  the  existing  physiological  conditions  as  to  preclude  the  adoption  of 
any  positive  rules  which  will  be  absolutely  universal  in  ap])lication,  but 
the  opportunities  for  success  will  increase  as  the  practitioner  who  essays 
to  do  such  operations  becomes  familiar  with  the  fundamental  laws  of 
dynamics,  the  science  which  treats  of  the  principles  of  force. 

Kequircmetits. 

As  the  application  of  bridgework  necessarily  embraces  a  combination 
of  surgical  and  mechanical  procedures,  a  degree  of  familiarity  with  the 
preceding  underlying  princi]jles  must  be  furtlier  su])])lemented  by  a  more 
or  less  exhaustive  knowledge  (jf  the  closely  allied  sciences  of  pathology 
and  therapeutics. 

With  these  attainments  as  a  foundation,  a  higher  a])])reciation  of  the 
actual  requirements  will  follow,  anrl  while  the  limitations  and  apparent 
simplicity  involved  would  seem  to  indicate  that  the  application  of  dental 


327 

bridges  does  not  usually  or  necessarily  present  serious  phases,  nor  extreme 
difficulties,  yet,  nevertheless,  the  operator  is  often  confronted  with  many 
interesting  and  some  perplexing  problems. 

In  proportion,  however,  as  such  fundamental  knowledge  in  the  com- 
posite may  be  acquired,  the  scope  of  opportunities  for  attaining  successful 
achievements,  and  for  the  solution  of  difficult  problems,  will,  of  course, 
be  enlarged. 

A  consideration  of  the  actual  rcqiiiroiiciifs  involved  in  the  practical 
and  successful  use  of  this  class  of  work  may  be  best  presented  by  class- 
ifying them  as  physiological,  mechanical  and  cosmetic,  the  relative  order 
in  which  they  present,  and  treating  them  from  the  separate  viewpoint  of 
each  respective  class. 

PhysiologicdL 

The  special  requirements  which  may  be  classified  as  presenting  a 
physiological  aspect  include  those,  of  course,  which  bear  materially  upon 
the  restoration  and  preservation  of  the  normal  condition  of  the  abutment 
teeth  and  contiguous  tissues. 

The  placing  of  the  roots  of  the  abutment  teeth  in 
HbUtmentS.  a   proper,    and    in    the    most    favorable   condition    is 

necessarily  the  first  consideration,  from  a  physiologi- 
cal viewpoint.  In  this  connection,  all  that  has  been  previously  said  con- 
cerning the  physiological  and  therapeutic  aspect  of  the  requirements  inci- 
dent to  the  preparation  of  roots  for  single  croivns  is  applicable  with  even 
greater  emphasis  to  the  treatment  of  those  which  are  to  serve  as  abut- 
ments for  bridgework. 

As  applied  particularly  to  the  question  of  the 
Devitalization  practicability  of  devitalizing  the  pulps  in  those  teeth 

Of  Pulp.  ivhich  arc  to  he  crowned,  and  which  are  to  further 

serve  as  supports  for  bridges,  the  previous  recom- 
mendations should  be  even  more  forcibly  observed,  for  the  following 
reasons : 

1.  Because  the  application  of  bridgework  of  any  form  should  always 
be  made  with  a  view  of  obtaining  the  highest  possible  degree  of  comfort 
and  permanency. 

2.  This  desirable  degree  of  comfort  and  permanency  will  usually 
obtain  and  increase  in  proportion  to  the  manner  in  which  the  sui^iorting 
or  abutment  teeth  may  be  placed  in  a  condition  offering  imnuumily  from 
subsequent  pathological  disturbances. 

3.  The  application  of  a  piece  of  bridgework  should  oi'icv  no  niore 


S2& 

Opportunity  for  the  action  of  deleterious  influences  of  any  nature  than 
existed  before  its  insertion. 

4.  Such  influences  may  be  induced  by  the  abnormal  stimulation  of 
the  contents  of  the  tubuli,  or  of  the  pulp— as  a  result  of  the  shock  inci- 
dent to  the  preparation  of  the  root ;  or  from  the  increased  or  diminished 
thermal  action,  which  irritation  may  result  in  a  rapid  or  in  a  slow  de- 
structive process ;  or  in  the  formation  of  "p^^^P  nodules"  ;  or  ultimate 
death  may  ensue  from  stasis  of  the  blood  supply,  or  from  peridental 
atrophy,  as  a  result  of  the  vise-like  fixation  of  the  tooth  in  its  socket. 

In  any  event,  an  abnormal  condition  is  established,  and  even  more 
mechanical  preparation  is  required  ;  hence,  the  most  conservative  judg- 
ment must  be  exercised,  with  a  view  of  placing  the  roots  in  the  most 
favorable  condition  possible. 

If  the  tooth  is  to  be  entirely  encompassed  with  a  "shell  or  telescope" 
crown,  this  will  usually  demand  that  the  pulp  be  removed,  and  that  the 
canals  be  placed  in  an  aseptic  condition  and  their  apices  filled  with  a  sub- 
stance which  will  act  as  an  impenetrable  barrier  to  the  subsecjuent  inva- 
sion of  pathogenic  organisms. 

The  exceptions  of  age,  as  previously  noted,  however,  will  guide  the 
operator  in  the  practicability  of  such  a  procedure,  but  with  these  excep- 
tions, and  since  the  pulp  is  recognized  as  being  purely  a  formative  organ, 
the  practice  under  these  conditions  should  be  more  or  less  general. 

I^Vdicnic  Considerations. 

The  success  of  this  class  of  work,  from  the  viewpoint  of  the  com- 
fort and  health  of  the  patient,  will  demand  that  every  means  for  obtain- 
ing as  hygienic  a  condition  as  possible  must  be  observed. 

To  obtain  this,  the  device  must  be  well  adapted  to  the  supporting 
teeth,  and  all  shoulders  and  pockets  which  would  invite  the  accumulation 
of  food  products  must  be  avoided.  All  ])arls  in  contact  must  also  be  well 
adapted  to  the  contiguous  soft  tissues,  and  any  sharp  and  irregular  edges 
whicli  might  cause  irritation  and  hypertrophy,  should  be  removed.  Lin- 
gual surfaces  which  will  be  sufficiently  accessible  to  the  bristles  of  a  tooth- 
brush to  admit  of  being  kept  reasonably  clean  must  be  provided,  and  as 
large  interproximal  spaces  as  is  consistent  should  exist. 

As  applied  particularly  to  "fixed"  bridgework,  a 

Pbyslo-Cbemlcal        physio-chemical  aspect  presents  which  makes  it  neces- 

^^P^Ct'  sary  tliat  tlie  mounting  medium  should  be  protected 

against  the  action   of  the  secretions,  and  thus   con- 

triljutc  to  the  hygienic  conditions,  as  well  as  to  the  preservation  of  the 

supporting  teeth,  and  to  the  permanency  of  the  operation. 


329 

In  this  connection,  also,  it  is  desirable  to  use  as  high  a  karat  of  gold 
as  permissible — when  gold  is  used  at  all — throughout  the  construction  of 
the  work,  and  that  all  exposed  surfaces  should  be  ivell  finished  and  highly 
polished  before  mounting,  in  order  that  the  susceptibility  to  discoloration 
through  chemical  action  of  the  secretions  of  the  mouth  ma}'  be  diminished. 

Indeed,  every  precaution  against  irritation,  and  against  affording  op- 
portunity for  the  action  of  the  products  of  fermentation,  should  invariably 
be  observed. 

Furthermore,  when  every  effort  to  provide  a  device  which  will  be  as 
self-cleansing  as  possible  has  been  made,  it  is  then  the  duty  of  the  operator 
to  instruct  the  patient  in  the  proper  manner  of  keeping  it  scrupulously 
clean,  and  to  advise  him  of  the  necessity  for  it.     If  all  of  these  precau- 


tions are  properly  taken  the  most  objectionable  features  of  "fixed"'  bridge- 
work  will  be  largely  removed,  and  when  they  can  not  be,  such  methods 
of  procedure  are  rarely  indicated. 


mechanical 

The  requirements  which  present  from  a  purely  mechanical  aspect  are 
so  closely  allied  with  those  which  have  been  considered  as  "physiological" 
as  to  be  scarcely  second  in  importance,  and  hence  success  will  of  neces- 
sity be  co-dependent  upon  an  observation  of  both  of  these  phases  of  the 
underlying  prerequisites. 

The   first   consideration    in   this   particular   con- 

Preparation  nection  is  obviously  that  pertaining  to  the  mechanical 

of  JIbUtmcntS.  preparation  of  the  abutments. 

While  the  requirements  involved  demand  the 
paralleling  of  the  remaining  walls  of  the  natural  teeth,  as  outlined  for  in- 
dividual crowns  in  Chapter  VI.,  the  proper  and  ready  adjustment  of  the 
hridge  after  the  respective  attachments  are  rigidly  united  also  demands 
that  the  axial  walls  of  the  abutments  must  be  reduced  until  presenting 
parallel  lines,  as  illustrated  in  Fig.  240,  A  and  R. 

From  these  illustrations,  presenting  more  or  less  common  conditions, 


330 

it  will  be  observed  that  a  lack  of  at  least  absolute  parallelism  between  the 
axes  of  the  projecting  ends  of  those  teeth  which  are  to  support  "tele- 
scope" crowns  will  preclude  the  subsequent  adjustment  of  the  bridge,  if 
the  crozi'iis  even  approach  a  close  fit  at  the  neck. 

Thus,  in  reducing  the  walls  of  the  abutments,  in  the  manner  indicated 
in  Chapter  XL,  this  requirement  must  be  observed,  and  if  sufficient  ac- 
curacy may  not  be  gauged  by  the  e}e,  exactness  may  be  obtained  from 
actual  measurement  by  the  use  of  a  small  pair  of  pointed  calipers,  by 
which  means  it  may  be  definitely  ascertained  whether  the  antero-posterior 
dimensions  between  the  cerznx  and  occlusal  ends  are  the  same. 

In  instances  where  a  "telescope"  crown  is  used  upon  one  abutment. 


F/^,24L 


in  combination  with  a  "dowel"  crown  upon  another,  and  where  the  axis 
of  the  root  supporting  the  latter  is  not  parallel  with  that  of  the  one  sup- 
porting the  former,  as  illustrated  in  Fig.  241,  it  will  be  necessary  to 
reduce  the  projecting  antero-posterior  walls  of  the  root  supporting  the 
"telescope"  crown,  imtil  they  may  be  made  nearly  parallel  with  the  root 
canal  which  is  to  receive  the  dowel,  in  order  that  the  assembled  bridge 
may  go  readily  to  place. 

Even  then  it  will  usually  be  necessary  to  enlarge  the  orifice  of  the 
canal  somewhat  to  admit  of  starting  the  bridge  toward  its  correct  adjust- 
men ;  and  when  tn'o  or  more  "dozuel  crozvns"  are  used  under  similar  con- 
ditions, it  will  be  necessary  to  observe  this  particular  requirement,  and 
then  also  to  allow  the  dowels  to  extend  into  the  canals  only  to  a  depth 
which  will  admit  of  the  proper  adjustment,  and  yet  insure  at  least  the 
minimum  of  necessary  strength  in  the  attachment  between  crowns  and 
roots. 

The  adaptation  of  the  attachments  to  the  abut- 
JTdaptation  ment  roots  must  be  sufficiently  strong  to  insure  per- 

OT  Attachments.         manency,   and   preclude   subsequent   mobility  or   dis- 
placement  when   subjected  to  stress,  and  must  also 
be  sufficiently  accurate  to  offer  no  possible  source  of  mechanical  irritation 
to  the  soft  tissues. 


331 

The  requirements  of  construction  demand  that 
Construction.  the  features  of  contact  with  the  contiguous  tissues, 

of   articulation    and    occlusion,    and   of    assemblage, 
nwxst  all  be  carefully  observed. 

The  relation  between  the  various  parts  of  the 
Contact.  bridge  and  the  soft  tissues  must  always  be  of  such  a 

nature  as  to  preclude  any  irritation  which  may  result 
in  subsequent  hypertrophy  and  attending  discomfiture. 

This  will  require  that  tlie  necks  of  all  facings,  and  all  surfaces  and 
edges  of  the  metal  construction  which  are  to  be  placed  in  contact  with  the 
tissues  must  be  nicely  rounded  and  perfectly  smooth,  and  that  any  undue 


Fiq.212 


pressure  which  would  be  likely  to  cause  superficial  or  capillary  stasis  must 
be  avoided. 

No  phase  of  the  construction  of  bridgework  is 
JlrtiCUlation  and         more  important  than  the  requirements  of  articulation 
Occlusion.  and  occlusion. 

Bearing  upon  the  requirements  in  this  particu- 
lar, it  has  been  previously  stated  that  by  uniting  two  or  more  teeth  "the 
movement  of  each  is  so  modified  and  restrained  as  to  enable  them  to  suc- 
cessfully withstand  more  force  than  the  sum-total  of  their  separate  .re- 
sistances," but  this  theorem  is  usually  applicable  only  to  those  teeth,  the 
axes  of  which  are  in  parallel  lines;  and  one  of  the  most  common  errors 
made  in  the  construction  more  particularly  of  "fixed"  bridgework 
is  the  increased  stress  which  is  thrown  upon  the  abutments,  without 
due  regard  for  the  resistance  offered. 

Hence,  in  the  construction  of  this  work  the  directions  of  the  least 
and  greatest  resistance  of  each  abutment  must  be  notctl,  and  the  articula- 
tion and  occlusion  so  adjusted  as  to  conform  as  closely  as  possible  thereto. 

In  this  connection,  it  must  be  remembered  that  the  abutments  will 
withstand  the  required  degree  of  z'crtical  stress — if  the  application  of 
the  piece  be  judicious,  but  that  any  tendency  toward  antero-posterior  or 
lateral  movement  lessens  the  permanency  of  the  work. 


For  this  reason  the  occkision  must  be  so  adjusted  as  to  control  or  at 
least  minimize  any  movement  in  these  directions ;  and,  as  the  cusps  in- 
crease in  depth,  the  stress  of  articulation  becomes  more  severe,  and  hence 
the  tendency  to  displacement  or  failure  is  thereby  increased. 

If  the  axes  of  the  abutment  roots,  however,  are  in  parallel  lines,  as 
illustrated  in  Fig.  242,  A,  any  antero-posterior  movement  either  in  the 
direction  of  greatest  or  least  resistance  is,  of  course,  mutual,  but  if  they 
are  not  parallel,  as  shown  in  Fig.  242,  B,  when  one  abutment  is  subjected 
to  stress  in  the  line  of  its  greatest  resistance,  the  other  receives  it  at  its 
least. 

In  properly  dealing  with  these  conditions,  the  occlusion  of  the  abut- 
ments and  intervening  dummies  in  the  latter  class  should  be  so  adjusted 
as  to  relieve  the  stress  of  the  occlusion  on  the  dummies  somewhat,  and  to 
throw  the  greatest  stress  in  the  line  of  the  greatest  resistance  on  each  indi- 
vidual ahutment,  but  each  abutment  must  always  receive  the  forces  of 
mastication  squarely  upon  its  occlusal  surface,  bucco-lingually,  in  order 
to  avoid  lateral  tendency. 

This  may  be  accomplished  only  by  a  proper  formation  of  the  cusps 
in  their  relation  to  the  opposing  teeth,  and  in  order  to  reduce  the  stress 
upon  the  abutments  the  cusps  of  the  dummies  should  alzvays  be  smaller 
bucco-lingually  than  those  of  the  crowns,  and  no  larger  than  the  absolute 
requirements  of  usefulness  will  demand. 

The  proper  arrangement  and  adjustment  of  the  articulation  and  oc- 
clusion of  bridgework,  in  accordance  with  these  requirements,  and  the 
usefulness  of  the  work,  together  with  a  proper  observation  of  precautions 
against  displacement  or  accident,  are  of  sufficient  importance  to  demand 
special  and  painstaking  attention,  and  the  best  results  will  doubtless  be 
afiforded  by  the  use  of  an  anatomical  articulator,  or  one  which  will  at  least 
admit  of  some  lateral  movement. 

When  the  construction  of  all  of  the  crowns  and 

Bsscmblage.  dummies  constituting  the  respective  parts  of  the  fin- 

ished bridge  has  been  completed  in  individual  form, 
and  since  the  piece  can  possess  no  greater  strength  than  its  weakest  point, 
the  assemblage  should  be  made  in  such  manner  as  to  insure  adequate  and 
uniform  strength  and  integrity. 

Cosmetic. 

The  cosmetic  requirements  incident  to  the  construction  of  this  class 
of  work  demand  that  conspicuous  or  unnecessary  display  of  gold  should 
be  avoided,  and  that  the  individuality  of  all  teeth  which  are  placed  within 
the  range  of  vision  should  not  be  destroyed  by  arranging  them,  or  their 


333 

backings,  in  such  close  proximity  as  to  leave  no  interproximal  spaces,  or 
no  separation  between  their  incisal  ends. 

The  artificial  teeth  should  be  selected  and  arranged  in  accordance 
with  the  requirements  of  color,  size,  shape,  alignment  and  characteristics, 
and  if  the  highest  artistic  results  are  to  be  obtained,  it  is  essentially  de- 
sirable that  the  "dummies"  within  the  range  of  vision  should  be  of  the 
same  length  as  the  abutment  crowns,  or  adjacent  natural  teeth. 

Whenever  occasion  indicates  the  observation  of  further  artistic  ef- 
forts, resort  may  be  made  to  tinting  with  mineral  paints  or  colored 
"bodies,"  or  to  the  insertion  of  small  gold  fillings,  as  a  means  of  making 
every  possible  efl^ort  to  have  the  artificial  substitutes  in  harmony  with 
their  environment. 


fixed'*  Bria^cwork* 


CHAPTER  XIX. 

Fundamental  Requirements  for  Success;  Good  Judgment,  Skill,  Preliminary  Con- 
siderations:   Devising  and   Planning  the   Procedure,    Construction  of 
Attachments,  "Bite"  and  Impression,  Models,  Precautions 
Incident  to  Investing,  Mounting  on  Articula- 
tor, Construction  of  "Dummies." 


In  the  construction  of  "fixed"  bridgework,  the  great  law  of  variation 
enters  so  prominently  into  each  case,  and  the  requirements  of  individual 
cases  are  in  turn  so  diversified,  as  to  practically  preclude  the  adoption  of 
specific  rules.  For  this  reason  it  is  apparent  that  no  special  methods, 
nor  modes  of  procedure,  may  be  classed  as  universally  applicable. 

Hence,  since  this  particular  field  of  efifort,  as  now  practiced,  is  con- 
paratively  modern,  we  can  not  be  guided  altogether  by  the  advantages 
which  might  be  derived  from  an  extensive  experience,  but  on  the  contrary, 
must  depend  to  a  large  extent  upon  close  clinical  observation  combined 
with  the  intuitive  or  accjuired  genius  of  a  practical  mind  and  hand,  so 
trained  as  to  work  in  consonance,  for  the  application  of  such  principles 
and  methods  as  will  seem  to  be  indicated,  and  to  ofl;er  the  most  favorable 
opportunity  for  achieving  successful  results. 

Tundamcittal  Kequireiticnts  for  Success. 

Thus  it  will  be  observed  that  the  successful  application  of  any  form 
of  dental  bridge,  and  particularly  of  a  "fixed"  type,  is,  first,  altogether  a 
matter  of  judgment,  a  faculty  which  may  only  be  acquired  or  developed 
by  observation  and  study,  while  success  or  failure  in  so  far  as  pertains  to 
the  construction  will  depend  largely  upon  the  display  of  skill,  or  lack  of 
it,  in  the  execution  of  detail. 


335 

This  faculty  of  good  judgment  may  be  best 
Good  Sudgmcnt.  acquired  by  first  obtaining  a  knowledge  of  the  cor- 
rect principles,  and  then  closely  observing  the  suc- 
cesses and  failures  as  they  present  from  time  to  time,  and  by  studying 
the  cause  and  effect  of  each  respective  result,  a  duty  which  every  con- 
scientious operator  essaying  to  do  this  class  of  work  owes  to  his  profes- 
sion, to  his  patient,  and  to  himself. 

The  acquirement  of  skill,  however,  is  a  different 
Jkill.  matter,  and  while  it  is  true  that  personal  equation 

enters  prominently  into  the  development  of  ability  to 
compreliend  and  successfully  execute  the  detail  of  all  pursuits,  and  par- 
ticularly of  those  which  combine  both  art  and  mechanics,  and  also  that 
we  may  learn  by  absorption,  yet,  nevertheless,  it  must  always  be  remem- 
bered that  while  genius  may  be  the  product  of  heritage,  and  individuality 
the  product  of  environment,  skill  is  but  the  product  of  a  gradual  de- 
velopment. 

To  summarize,  then,  the  success  of  this  class  of  work  in  any  of  the 
various  phases  of  its  application,  will  be  co-extensive  with,  and  indeed 
dependent  upon,  a  conscientious  observation  of  two  fundamental  princi- 
ples, i.  e.,  judgment  in  applieation,  and  ^/e/7/  in  execution,  and  will,  of 
course,  increase  in  proportion  as  these  faculties  may  be  developed. 

In  questions  of  doubt  the  conservative  rather  than  the  radical  pro- 
cedure should  always  be  given  precedence,  as  the  best  interests  of  the 
patient,  and  the  reputation  of  the  operator  are  at  stake,  and  both  should 
invariably  be  conserved. 

Prcliitiinarv  Considerations. 

As  '"fixed"  bridgework  is  essentially  an  assemblage  of  "attachments," 
or  "abutment  pieces"  and  intervening  or  adjacent  "dummies,"  the  sub- 
ject can  doubtless  be  presented  in  the  most  practical  and  comprehensive 
manner  by  considering  it  from  the  respective  viewpoints  of,  first,  the  ap- 
plication and  construction  of  "attachments"  or  "abutment  pieces" ;  second, 
the  application  and  construction  of  the  "dummies"  which  are  to  substi- 
tute the  missing  teeth,  and  third,  the  final  "assemblage"  of  the  various 
parts. 

The  presentation  of  each  of  these  phases  of  the  subject,  however, 
ma}'  be  properly  prefaced  by  the  consideration  of  a  few  general  require- 
ments which  should  invariably  be  observed,  and  which  will  be  found  to 
be  productive  of  the  best  and  most  certain  results,  and  thus,  in  the  long 
run,  to  expedite  the  procedure. 


336 

The  conditions  of  each  case   should  be  closely 

Devising  and  Planning     observed ;  the  method  of  procedure  which  seems  best 

the  Procedure,  indicated  should  be  selected,  and  the  bridge  carefully 

planned  before  any  of  the  actual  work  incident  to  its 

construction  is  attempted. 

In  this  connection  the  observation  of  such  requirements  may  be  facili- 
tated, particularly  in  extensive  cases,  by  taking  impressions  and  securing 
good  models,  the  same  to  be  used  only  as  an  aid  to  devising  and  plan- 
ning the  procedure. 

When  the  method  of  procedure  has  been  decided 
Construction  of  upon    each    and    every    "attachment,"    or    "abutment 

JIttacbmentS.  piece"  should  first  be  made  and  completed  separately, 

except,  of  course,  that  they  need  not  be  polished. 
This  applies  to  any  style  of  attachment  with  the  exception  of  dowel 
crowns,  in  which  instances  only  the  cap  and  dowel  should  be  thus  com- 
pleted, at  least  until  all  of  the  facings  have  been  selected. 

The     completed    "attachments"     or     "abutment 
"Bite"  pieces"  should  then  be  accurately  adjusted  to  posi- 

and  Impression.  tion  on  the  abutments,  with  wax  or  temporary  stop- 

ping to  sustain  them  in  their  proper  relation,  if 
necessary,  and  an  accurate  occluding  "bite"  in  wax,  and  an  impression  in 
plaster  then  taken. 

A  zca.v  "bite"  is  to  be  preferred  to  modeling  composition  or  other 
materials,  because  of  the  ease  with  which  it  may  be  adjusted  to  the  model 
without  danger  of  breakirlg  off  the  plaster  teeth ;  and  a  plaster  impression 
is  always  indicated  because  the  employment  of  any  material  for  this  pur- 
pose which  will  drazv  perceptibly  in  removing  from  the  mouth  is  not 
reliable,  and  hence  the  accurate  replacement  of  the  parts  in  such  impres- 
sions is  not  insured. 

Good  reliable  models  of  plaster  should  then  be 

models.  procured,    the    wax    "bite"    adjusted,    and    the    case 

mounted  upon  the  articulator. 

In  this   connection  plaster   models   are   always   preferable   to   those 

made  of  any  of  the  investment  materials,  for  the  reason  that  strength  and 

accuracy  of  outline  are  essential,  and  that  such  qualities  are  not  possessed 

in  the  greatest  degree  by  models  made  of  investment  materials. 

Before   filling   tlie   impression  the  method   ulti- 

Precautions  Incident      matcly  to  be  observed  in  investing  the  case  for  final 

to  Investing.  soldering  should  be  noted.     If  the  "abutment  pieces" 

are  to  remain  in  situ  upon  the  model,  after  trimming 

it  down  and  investing,  and  during  the  process  of  soldering,   which  is 


OvV 

ahvays  advisable  in  extensive  cases,  it  must  be  carefully  observed  that 
their  interior  is  well  filled  with  the  plaster  in  pouring-  the  model,  in  order 
to  prevent  air  spaces  which  not  infrequently  result  in  fusing  the  parts 
during  the  process.  If  the  "abutment  pieces"  are  to  be  detached  from  the 
model,  however,  previous  to  investing,  as  is  indicated  in  small  cases,  pro- 
vision for  facilitating  the  same  should  be  observed  by  partially  filling 
their  interior  with  melted  wax. 

All  cases  involving  any  number  of  the  posterior 
mounting  teeth  should  be  mounted  and  constructed  upon  some 

on  JlrtlCMlatOl*.  form  of   "anatomical"   articulator,   or   one   which   at 

least  affords  some  lateral  movement.  This  is  essen- 
tial for  the  reason  that  many  failures  in  bridgework  can  be  attributed 
directly  to  faulty  occlusion,  and  the  success  of  all  such  cases  will  depend 
largely  upon  the  degree  of  accuracy  in  this  particular. 

Like  the    "attachment"    or    "abutment    pieces," 

Construction  of  each  of  the  intervening  "dummies"  should  be  co)u- 

**  Dummies."  plctcd  previous   to   the   final   assemblage   of   all   the 

parts.     \\'hile  this  may  seem  like  an  unnecessarily 

circuitous  procedure,   its   observance   eliminates   any  possible   danger  of 

fracturing  the  porcelain  facings  during  the  process  of  the  final  soldering ; 

or,  of  a  change  in  the  relation  of  the  parts  accruing  from  the  shrinkage 

of  so  large  a  quantity  of  solder  carried  to  the  state  of  fusion  at  one  time, 

and  greatly  diminishes  the  work  incident  to  the  final  assemblage. 


*^jfttacbiiiem$"  or  "Jlbutment  Pieces/* 


CHAPTER  XX. 

Attachments  to  the  Roots  of  Teeth :  Shell  or  Telescope  Crowns ;  Application,  Con- 
struction.    Dowel  Crowns,   Application,   Construction.     Incising  Natural   Crowns 
of  Sound  Teeth.    Attachments  to  the  Natural  Crown:  Open-face  Crowns;  Indi- 
cations and  Contraindications,  Application,  Preparation  of  Tooth,  Construc- 
tion,   Variation    of    Method,    Fusible    Metal    Models,    Seamless    Method, 
Application    to    Molars    and    Bicuspids.      Partial    Crown    Attachments : 
Indications  and  Contraindications.     Application.     Plate  and  Pin  Attach- 
ments :    Adaptation,    Pins,    Reinforcement.        Groove    Attachments : 
Indications,   Preparation   of   Natural    Crown,    Construction.     Inlay 
Attachments  :  Indications,  Requirements,  Cavity  Formation,  Con- 
struction.    Taggart's   Method   of   Casting.     Telescope   Attach- 
ments:   Indications,    Po'ssible    Objections,    Possible    Advan- 
tages, Construction.     Temporary  Attachments  :  Indications, 
Application.       Occlusal     and     Lingual      Supports :      Oc- 
clusal      Supports,       Indications,       Application.        Lin- 
gual        Supports :         Indications,         Application. 


In  the  development  of  "fixed"  bridgework  innumerable  methods  of 
securing  attachment  to  the  remaining  natural  teeth  have  been  devised, 
but  as  many  of  them  have  proven  impracticable,  only  those  of  acknowl- 
edged usefulness  and  practicability  at  the  present  time  will  be  presented. 

These  may  be  considered  in  two  general  classes :  first,  those  wherein 
the  attachment  is  made  to  the  roots  of  the  remaining  natural  teeth,  and 
second,  those  wherein  the  natural  crown  of  the  tooth  is  conserved  and  the 
attachment  made  to  it. 

JIttacbmeiits  to  m  Roots  of  Ceetb. 

Irrespective  of  the  desirability  of  conserving  the  natural  crowns  of 
those  teeth  which  are  to  support  the  bridge  wherever  possible,  and  par- 
ticularly in  the  anterior  part  of  the  mouth,  the  application  of  artificial 
crowns  well  adajjted  io  the  rrxjts  of  teeth  must  be  regarded  as  the  best, 
most  universally  applicable  and  permanent  means  of  attachment  for 
"fixed"  bridges. 


339 

Shell  or  telescope  Crowns. 

Of  all  the  methods  employed  the  shell  or  telescope  crown  doubtless 
encompasses  a  greater  sphere  of  usefulness  and  affords  a  greater  range 
of  application  than  any  other  one  style  of  attachment. 

For    cosmetic    reasons,    the   application    of   this 
JHPpHcatiOlU  style  of  crown  must  necessarily  be  confined  exclu- 

sively to  the  posterior  teeth.  In  the  upper  arch  such 
crowns  should  seldom  if  ever  be  used  anterior  to  the  second  bicuspid,  but 
in  the  lower  arch  where  the  teeth  are  usually  less  conspicuous  they  may 
occasionally  be  used  as  far  forward  as  the  first  bicuspid.  The  flagrantly 
inartistic  practice  of  employing  such  crowns  on  the  cuspids  or  incisors, 
however,  is  unnecessary  and  unwarrantable,  in  any  case. 

When  it  has  been  decided  that  such  crowns  are 
Construction.  implicated  for  attachments,  the  root  or  roots  should 

be  prepared,  and  the  crowns  constructed  in  accord- 
ance with  the  prescribed  procedures  as  previously  outlined. 

As  a  general  rule  they  should  be  completed  in  proper  form  first,  as 
mentioned,  and  this  is  imperative  in  bridges  involving  more  than  three 
teeth,  and  particularly  when  two  or  more  crowns  of  this  style  are  em- 
ployed in  the  same  fixture,  for  the  reason  that  the  bands  must  otherwise 
be  detached  from  and  replaced  upon  the  model  so  often  as  to  possibly 
thereby  endanger  the  accuracy  of  the  final  result. 

Dowel  Crowns. 

Manifestly  the  next  most  important  and  generall}'  useful  method  of 
attachment  may  be  obtained  from  the  employment  of  dowel  crowns,  and 
under  this  classification  is  included  all  of  the  various  styles  wherein  a 
dowel  is  used. 

When  used  as  an  attachment  for  bridgework,  however,  a  narrow 
band  encircling  the  end  of  the  root  should  invariably  be  employed  in 
preference  to  a  simple  plate  adapted  only  to  the  basal  surface,  as  the  pro- 
tection thus  afforded  will,  doubtless,  add  to  the  preservation  of  the  root, 
and  the  stability  of  the  attachment.  It  must  not  be  forgotten,  however, 
that  the  success  of  a  band  depends  entirely  upon  the  degree  of  thorough- 
ness observed  in  preparing  the  periphery  of  the  root,  and  in  adapting  the 
band  to  it,  in  order  to  preserve  a  continuity  of  its  surface,  and  thus  avoid 
the  possibility  of  irritation. 

The  application  of  this  style  of  crown  is  always 

Hpplication.  indicated  on  the  si.x  anterior  teeth,  and  for  cosmetic 

reasons  should  invariably  be  employed  on  the  first, 

and  frequently  on  the  second  bicuspids,  wherever  the  natural  crown  has 


340 

been  wholly  or  perhaps  even  partially  destroyed  by  caries,  and  where  it 
may  not  seem  warrantable  or  expedient  to  make  an  effort  to  conserve  it, 
or  its  remaining  portions. 

Where   dowel   crowns   of   any    style   are   to   be 

Construction.  employed   as   attachments,   they   should  be   made   in 

accordance    with   the   previously    described    require- 
ments of  root  preparation,  adaptation  and  construction. 

The  caps,  including  dowels,  should  be  completed  first,  however,  and 
the  "bite"  and  impression  then  taken,  and  models  procured.  This  admits 
of  the  proper  selection  and  adjustment  of  the  facings  in  their  relation  to 
the  caps  and  to  each  other,  after  which  the  caps  with  their  respective 
facings  should  be  detached  and  soldered  separately,  previous  to  the  final 
assemblage  of  the  entire  piece.  For  the  reasons  already  mentioned,  this 
procedure  should  be  observed  in  all  cases  involving  two  or  more  crowns, 
and  provision  for  their  detachment  from  the  model  should  be  observed 
before  filling  the  impression. 

Incising  natural  Crowns  of  Sound  CccfD. 

The  question  of  sacrificing  the  natural  crowns  of  sound  teeth,  par- 
ticularly in  the  anterior  part  of  the  mouth,  for  the  purpose  of  substituting 
artificial  ones  as  supports  for  bridgework  is  undoubtedly  highly  im- 
portant, and  demands  the  most  conscientious  thought  and  deliberation 
on  the  part  of  the  operator,  for  the  reason  that  it  is  not  within  the 
province  of  our  art  to  perfectly  restore  the  natural  condition. 

It  is  quite  generally  conceded,  however,  that  such  a  procedure  be- 
comes warrantable  in  proportion,  first,  to  the  disfigurement  caused  by  the 
missing  teeth  ;  second,  to  the  normal  or  abnormal  position  of  such  natural 
crowns  in  their  relation  to  the  adjacent  teeth;  third,  to  the  absence  of 
practical  indications  for  other  or  better  means  of  supplying  the  missing 
ones  than  by  bridgework ;  fourth,  to  the  inconvenience  to  the  patient  of 
wearing  a  partial  denture,  their  natural  abhorrence  of  the  same,  or  the 
possible  injury  to  the  natural  teeth  that  might  result  from  abrasion,  in 
their  use;  anrl  fifth,  to  the  ability  of  the  operator  to  restore  them  in  a 
practical,  artistic  and  reascmably  ])ermanent  manner. 

While  the  age,  and  ])ossibly  the  sex,  of  the  patient  has  a  material 
bearing  u]jon  the  ])racticability  of  such  a  course,  in  any  event,  still  we 
may  often  be  justified  in  adopting  such  a  procedure  in  at  least  two  general 
classes  of  cases. 

First,  in  those  cases  where  an  extensive  bridge  may  seem  indicated, 
and  where  a  reasonably  permanent  style  of  crown  is  to  be  employed  upon 
the  other  abutment  roots.     If  all  other  abutment  roots  are  to  be  treated 


341 

in  a  manner  which  will  seem  to  offer  greater  opportunities  than  would 
likely  be  secured  by  any  style  or  method  of  attachment  other  than  a  crown, 
one  should  not  hesitate  to  sacrifice  the  natural  crown  of  a  tooth  which  is 
needed  for  support,  and  substitute  an  artificial  one,  as  a  means  of  afford- 
ing greater  strength  to  the  entire  piece  and  more  artistic  and  permanent 
results,  and  particularly  where  the  cutting  oft'  of  one  or  two  crowns  of 
sound  teeth  makes  possible  the  secure  fixation  of  substitutes  for  several 
missing  ones. 

Second,  in  many  of  those  not  uncommon  cases  where  conspicuous 
teeth  have  been  lost  through  accident  or  from  other  causes,  in  an  other- 
wise perhaps  good  and  uninterrupted  arch.  By  sacrificing  the  natural 
crowns  of  the  tooth  or  teeth  adjacent  to  the  space,  as  the  requirements 
may  indicate,  the  missing  ones  may  often  be  supplied  in  a  "fixed"  manner 
by  attachment  to  the  artificial  substitute,  with  results  more  comfortable 
and  serviceable,  and  less  objectionable,  inconvenient  and  embarrassing 
to  the  patient ;  and  with  artistic  and  permanent  possibilities  in  proportion 
to  the  skill  evidenced  in  the  adaptation  and  construction  of  the  work. 

JlftiicMticnts  (o  the  natural  £r^wn. 

Under  the  classification  of  attachments  to  the  natural  crown  may  be 
included  all  methods  other  than  artificial  crowns,  or,  all  of  those  wherein 
an  effort  is  made  to  obtain  adequate  anchorage  and  fixation  and  yet  con- 
serve as  much  as  possible  of  the  remaining  natural  crown  of  the  tooth  so 
employed. 

Whilst  such  conservation  of  tooth  structure  is  manifestly  a  desirable 
procedure,  and  one  which  should  be  observed  wherever  the  requirements 
and  possibilities  seem  favorable,  yet  it  nevertheless  often  happens  that  the 
natural  crowns  thus  utilized  are  saved  only  for  the  time  being,  to  be  lost 
subsequently  as  the  result  of  methods  which  are  contraindicated,  un- 
reliable or  inadequate. 

Hence  the  employment  of  this  class  of  attachments  demands,  on  the 
whole,  the  exercise  of  rare  good  judgment,  combined  with  the  utmost  of 
painstaking  effort  on  the  part  of  the  operator,  and  will  be  successful  only 
in  proportion  thereto. 

Open-face  Crowns. 

Under  this  classification  the  so-called  "open-face"  crown,  which,  as 
the  name  implies,  consists  of  a  telescope  crown  with  the  "face"  or  labial 
surface  so  cut  away  as  to  expose  as  much  as  possible  of  this  portion  of  the 
natural  crown,  has  been  perhaps  the  most  generally  employed  method  of 
attachment. 


342 

The  real  and  practical  value  of  this  particular  style  of  attachment, 
however,  is  always  a  question  of  very  great  importance  for  the  reason  that 
one  of  two  conditions  incident  to,  or  arising  from,  their  use  does 
or  may,  result.  Either  less  destruction  of  the  natural  crown  than  for  any 
other  style  of  attachment  is  demanded ;  or,  an  infinitely  greater  degree  of 
destruction  may  result  from  their  injudicious  application,  or  faulty  adap- 
tation. 

Of  the  several  influences  which  may  have  been  responsible  for  retard- 
ing the  practicability  and  success  of  modern  "fixed"  bridgework,  the  very 
greatest  one  can  doubtless  be  attributed  to  the  indiscriminate  and  unskill- 
ful application  of  such  attachments,  particularly  when  they  may  be  classed 


/v'y.  243. 

as  simple  bands,  and  more  good,  sound  teeth  have  been  lost,  and  more  fail- 
ures recorded  through  this  pernicious  practice  than  from  any  other  one 
source. 

Hence,  the  indiscriminate  use  of  this  class  of  attachments  should 
be  more  or  less  generally  condemned  for  the  reason  that  their  appli- 
cation may  result  in  injury  to,  instead  of  conservation  of,  the  sup- 
porting natural  crown,  and  thus  prove  a  menace  to  the  possible  success 
and  permanency  of  the  structure  of  which  they  form  a  part ;  and  for  the 
further  reason  that  they  are  almost  always  conspicuously  inartistic. 

Two  typical  cases  are  illustrated  in  Fig.  243,  where  injudicious  appli- 
cation and  faulty  adaptation  of  such  attachments  has  ended  in  the  loss  of 
the  supporting  teeth.  It  is  quite  safe  to  prophecy  such  a  result;  or  at 
least,  the  possible  loss  of  the  natural  crown  from  hidden  caries,  if  the 
adaptation  be  not  accurate. 

Notwithstanding  these  unfavorable  features,  however,  there  are  occa- 
sional instances  where  this  style  of  attachment  may  be  indicated,  and 
where  its  use  may  be  productive  of  serviceable  results  in  proportion  as 
the  fixture  may  be  carefully  adapted  and  properly  constructed. 

The     indications     for    the     successful     use     of 
Indications  and         such  attachments  would  always  confine  their  applica- 
Contraindications.       tion  exclusively  to  the  six  anterior  teeth,  and  par- 
ticularly to  the  upper  cuspids,  and  to  the  lower  cuspids 


343 

and  incisors,  or,  to  those  teeth  where  the  normal  shape  and  proportions 
of  the  natural  crowns  are  more  or  less  favorable. 

The  normal  average  inequality  between  the  dimensions  of  the  crozvns 
and  necks  of  the  upper  incisors,  and  of  the  bicuspids  and  molars,  both 
upper  and  lower,  however,  usually  demands  so  much  mutilation  of  the 
natural  crown  in  its  preparation  as  to  preclude  their  application  to  these 
leeth,  or,  at  least  to  contraindicate  their  employment. 

The  fact  that  the  application  of  this  style  of  attachment  admits  of 
the  telescoping  principle,  thereby  answering  the  same  purpose  as  an  all 
gold  crown  without  its  objectionable  features  as  applied  to  anterior  teeth, 
and  thus  not  demanding  the  sacrifice  or  excising  of  the  natural  crown, 
often  makes  it  possible  to  secure  a  greater  degree  of  strength  in  the  attach- 
ment to  the  root,  by  thus  distributing  the  stress  over  the  entire  Jength  of 
the  tooth,  than  would  be  likely  to  accrue  from  sacrificing  the  natural 
crown  and  substituting  a  dowel  crown.  This  is  a  particularly  advan- 
tageous feature  in  extensive  bridges  in  which  anterior  teeth  are  involved, 
and  especially  in  the  lower  arch  where  the  roots  are  small,  and  yet,  since 
it  must  be  acknowledged  that  the  attachment  between  such  a  crown  and 
the  supporting  tooth  is  usually  of  a  more  or  less  temporary  nature,  due  to 
the  possible  penetration  of  saliva  into  the  exposed  joint,  and  the  gradual 
dissolution  of  the  cement,  great  care  must  be  observed  in  securing  the 
most  accurate  adaptation  possible,  especially  when  it  is  to  be  used  in  con- 
junction with  another  style  of  attachment,  such  as  a  crown,  which  would 
perhaps  ofifer  greater  permanency  when  cemented  to  place. 

If  the  application  be  confined  to  the  class  of  teeth 

applications.  indicated ;  if  the  approximal  surfaces  of  such  teeth 

are  properly  trimmed  so  as  to  present  parallel  lines ; 
if  all  other  coronal  proportions  are  reduced  sufficiently  to  admit  of  the 
accurate  adjustment  of  a  crown  and  not  a  simple  band;  if  the  adjustment 
of  the  circular  portion  to  the  neck  is  accurate ;  if  the  entire  lingual  surface 
and  incisal  end  of  the  tooth  is  so  covered  as  to  prevent  the  attach- 
ment from  being  forced  root-wise;  if  the  labial  surface  is  so  trimmed 
as  to  have  as  little  gold  show  as  possible ;  if  all  edges  are  then  brought 
to  "self-cleansing"  points,  and  the  whole  then  made  strong 
enough  to  retain  its  shape,  and  admit  of  favorable  occlusion  with  the 
opposing  teeth,   such  attachments  may  be  expected  to  offer  reasonably 

permanent  results. 

In  the  preparation  of  the  natural  crown  for  the 

Preparation  of  reception  of  an  attachment  of  this  kind  the  paralleling 

COOtb.  of  the  approximal  walls  should  receive  attention  first. 

If  an  adjacent  tooth  be  present,  adequate  space  sliould 


344 

be  previously  gained,  and  then  the  required  trimming  on  each  side  may  be 
easily  accomplished  with  coarse  disks,  or  very  thin  stones. 

In  this  procedure  it  is  necessary  to  remove  only  enough  to  admit  of  so 
reducing  the  coronal  dimensions  (Fig.  244  A)  as  to  make  possible  the 
accurate  adjustment  of  the  crown  to  the  cervix  (Fig.  244  B),  and  care 
should  be  exercised  to  protect  the  adjacent  natural  crown,  if  one  be  present, 
from  mutilation  during  the  operation.  The  trimming  of  these  surfaces 
should  have  a  slight  lingual  tendency  (Fig.  244  C),  and  should  be 
continued  until  a  measurement  wire  twisted  taut  at  the  cervix  may  be 
easily  removed. 


Fi<j.244.a  ! 


FJcj.244.  h. 


F/(^.244.  c. 


The  lingual  surface  should  then  be  ground  away  sufficiently  to  admit 
of  the  presence  of  the  crown  without  interfering  with  the  occlusion  of 
the  opposing  teeth,  and  the  incisal  end  should  then  be  beveled  lingually 
as  a  means  of  affording  a  definite  edge  to  which  this  portion  of  the  attach- 
ment may  be  finished,  and  a  shoulder,  which,  when  covered,  will  prevent 
its  being  forced  root-wise  beyond  its  proper  relation.     (Fig,  245.) 

In  the  construction  of  such  attachments  a  thick- 

£on$truction.  ness  of  gold  should  be  used  which  may  be  easily  and 

readily  conformed  to  the  tooth,  but  after  being 
properly  adapted,  it  must  be  subsequently  reinforced  in  such  manner  as  to 
insure  adequate  and  uniform  strength. 


345 

When  the  measurement  has  been  taken  with  wire,  as  usual,  a  band  of 
29  or  30  gauge  22  K.  gold  should  be  cut  of  the  same  length  as  the  meas- 
urement, and  of  a  width  greater,  or,  at  least,  equal,  to  the  length  of  the 
natural  crown  from  gum  line  to  incisal  end,  and  then  made  in  circular 
form  and  soldered  with  22  or  20  K.  solder. 

The  cervical  end  should  now  be  trimmed  to  follow  the  curvature  of 
the  gum,  nicely  rounded,  and  then  fitted  to  this  portion  of  the  tooth, 
allowing  it  to  pass  a  short  but  uniform  distance  beneath  the  free-margin. 
(Fig.  246  A.) 

When  the  desired  adaptation  at  this  point  has  been  secured,  both  the 
labial  and  lingual  surfaces  should  be  trimmed  away  as  indicated  in  Fig. 


Ficj.  245. 

246  B.  This  reduces  the  exposed  band  upon  the  labial  surface  to  the 
proper  width,  brings  all  labial  edges  to  the  desired  point,  to  be  self- 
cleansing,  and  allows  the  lingual  band  and  approximal  surfaces  to  be 
closely  adapted  to  the  tooth. 

A  piece  of  pure  gold  about  34  gauge  should  now  be  annealed  and  bur- 
nished to  the  lingual  surface  of  the  teeth,  with  this  portion  of  the  crown 
in  place,  until  a  close  contact  with  the  tooth  and  entire  lingual  edge  of 
band,  is  obtained.  (Fig.  246  C.)  The  two  should  then  be  removed, 
wired  together,  if  necessary,  and  attached  with  just  enough  solder  to  efifect 
union  all  around,  during  which  the  whole,  and  particularly  the  narrow 
labial  band  and  pure  gold  back,  may  be  uniformly  reinforced  upon  the 
outer  surface  with  the  same  karat  solder.  If  the  approximal  surface  of 
the  attachment  does  not  restore  the  contact  point  with  the  adjacent  tooth, 
sufficient  fullness  to  insure  its  restoration  should  be  made  at  this  time. 
This  may  be  done  with  small  pieces  of  plate  gold,  or  with  solder  alone. 


346 


The  crown  should  then  be  again  placed  in  position  on  the  tooth  and 
finished  with  disks  until  the  adaptation  is  completed  (Fig.  246 D),  when 
the  final  impression  with  it  and  the  other  abutment  pieces  in  place  may  be 
taken. 

A  more  simple  method  is  sometimes  employed, 
in  which  only  the  labial  portion  of  the  band  is  cut 
away  after  proper  adaptation  to  the  cervix  has  been 
secured,  and  the  remaining  lingual  portion  is  bent 
down  and  burnished  to  place  directly  upon  the  tooth.  By  cutting  out  a 
V-shaped  piece  from  the  immediate  center,  this  may  be  done,  and,  of 
course,  saves  material  and  does  not  require  the  attachment  of  a  separate 
backing,  but  the  adaptation  is  usually  less  accurate. 


Uariation  of 
method. 


Tusible 
metal  models. 


nq.246. 

The  construction  of  such  attachments  upon  fusi- 
ble metal  models  of  the  tooth  is  also  sometimes  recom- 
mended as  facilitating  the  procedure,  but  as  the  crown 
should  pass  slightly  beneath  the  gum,  such  models 
are  not  accurate  unless  a  temporary  band  of  German  silver  or  copper,  so 
adjusted,  and  properly  adapted,  is  previously  fitted,  and  the  model  poured 
with  this  in  place  in  the  impression.  Under  such  conditions  a  more  or 
less  accurate  result  may,  of  course,  be  obtained. 

The  seamless  method,  as  referred  to  in  Chapter 
Seamless  method.        VI  may  also  be  employed  in  the  construction  of  such 
attachments,  and  this  procedure  affords  an  accurate 
fitting  crown  when  the  labial  surface  has  been  cut  away — provided  a  tem- 
porary band  has  been  previously  adjusted — which  is  always  necessary  for 
the  ab.ove-mentioned  reasons. 

While  this  style  of  attachment  is  sometimes  em- 
ployed on  molars  and  bicuspids,  such  application  is 
to  be  generally  condemned  for  the  reasons  previously 
given.  When  used  n])on  these  teeth  they  practi- 
cally become  simple  bands,  and  other  more  permanent 
means  of  attachment  are  possible  and  should  be  employed. 


Jlpplications 

to 

molars  and  Bicuspids. 


347 

A  variation  of  typical  cases  in  which  the  application  of  the  open- 
face  crown  would  be  more  or  less  practicable  are  illustrated  in  Fig.  247. 
In  these  cases,  it  will  be  observed  that  such  an  attachment  is  used  to 
support  one  or  both  ends  of  small  anterior  bridges,  but  only  the  anterior 
end  of  those  involving  the  posterior  teeth. 


Fi(j.  24  i 


Partial  Crown  jflttacbmcnts. 

Ranking  next  to  the  open-face  crown  from  the  viewpoint  of  general 
usefulness  may  be  considered  that  class  of  attachments  which,  while 
including  nearly  all  forms  of  "plates,"  "inlays"  and  partial  crowns,  may 
be  generally  designated  under  the  classification  of  partial  crown  attach- 
ments. 

This  class  of  attachments  differs  from  the  open-face  crown  in  that 
as  a  general  rule  the  telescope  principle  is  not  used,  and  hence  the  natural 


348 

crown  is  not  completely  encircled  with  a  band.  Thus  only  the  lingual  or 
linguo-occlusal  surfaces  are  usually  involved,  and  the  fixation  of  the  piece 
is  secured  to  them  by  various  mechanical  means. 

This  avoids  the  necessity  for  the  display  of  any  gold  upon  the  labial 
or  buccal  surface,  and  thereby  makes  such  attachments  practicall\  invisi- 
ble, which  is  always  a  desirable  feature  as  applied  particularly  to  the  eight 
or  ten  anterior  teeth,  when  it  may  be  accomplished  by  means  which  will 
offer  a  reasonable  degree  of  permanency. 

The  usefulness  of  any  attachment  of  this  kind,  however,  depends 
largely  upon  the  same  favorable  indications  for  their  employment,  and  the 
same  degree  of  accuracy  in  their  adaptation  as  has  been  described  in  con- 
nection with  open-face  crowns. 

For  this  reason,  while  their  judicious  employment  and  skillful  adap- 
tation enables  them  to  occupy  a  sphere  of  usefulness,  like  many  other 
methods,  and  so-called  systems,  they  are  by  no  means  to  be  regarded  as 
being  universally  applicable,  and  hence  they  will  be  successful  only  in 
proportion  as  they  may  be  judiciously  used. 

The  indications  for  any  of  these  special  forms  of 
Indications  attachments,  in  general,  would  usually  confine  their 

and  Contraindications,   application  to  the  crowns  of  such  teeth  as  may  offer 
opportunity  for  accurate  adjustment,  as  a  means  of 
supporting  one  or  perhaps  both  ends  of  small  bridges ;  of  supporting  one 
end  of  larger  bridges  when  a  crown  is  used  on  the  other  end,  or  of  sup- 
porting a  single  missing  tooth. 

As  compared  with  the  possible  longevity  of  a  well-adapted  full  crown, 
however,  such  attachments,  no  matter  how  conservatively  employed  or 
skillfully  adapted,  while  involving  a  less  radical  procedure,  are  usually 
to  be  regarded  as  being  of  a  more  or  less  temporary  nature ;  yet  in- 
stances of  great  permanency  have  been  recorded. 

While  innumerable  methods  of   obtaining  suit- 

Jlpplication.  able  mechanical  fixation  to  the  natural  crown  have 

been  suggested,  many  have  proven  impracticable,  and 
hence  only  those  which  are  regarded  favorably  will  be  considered.  In  the 
application  of  any  of  them,  however,  at  least  three  cardinal  features  must 
be  observed:  First,  the  supporting  natural  crown  must  be  so  prepared  as 
to  admit  of  accurate  adjustment  to  it  and  to  the  occlusion,  and  to  afford 
adequate  means  for  mechanical  retention  ;  second,  this  preparation  must 
rnclude  an  observation  of  the  requirements  of  parallelism,  which  will  admit 
of  the  ready  adjustment  of  the  structure  of  which  it  will  subsequently  be 
only  a  part,  and  third,  the  attachment  must  possess  sufficient  inherent 
strength  to  insure  stability. 


649 

Plate  ana  Pin  JItucbments. 

As  applied  exclusively  to  the  six  anterior  teeth,  and  particularly  to 
the  incisors,  perhaps  the  best  and  most  expedient  attachment  of  this  kind 
embraces  the  adaptation  to  the  lingual  surface  of  the  natural  crown  of  a 
simple  plate  with  supporting  pins. 

In  this  procedure  the  tooth  should  be  properly  pre- 

Jldaptation.  pared,  and  a  plate  of  34  gauge  pure  gold  then  closely 

adapted  to  the  entire  lingual  surface  from  just  slightly 

beneath  the  cervix  to  the  extreme  incisal  edge,  and  just  far  enough  around 


F/q.  248. 


the  approximal  surfaces  toward  the  labial  to  bring  the  margins  beyond  the 
contact  point,  or  to  a  self-cleansing  area.  It  will  be  observed  at  once 
that  this  will  require  that  these  surfaces  be  so  prepared  as  to  admit  of 
ready  removal  and  replacement  of  the  plate  without  danger  of  distorting 
its  shape,  a  precaution  very  similar  to  that  required  for  an  open-face 
crown,  as  previously  illustrated. 

Pure  gold  should  be  employed  because  of  the  facility  with  which  it 
may  be  closely  adapted  to  the  tooth,  and  the  adaptation  may  be  accom- 
plished either  by  burnishing  or  by  swaging  on  a  fusible  metal  model  or 
die  of  this  portion  of  tooth,  as  may  be  preferred. 

When  the  plate  has  been  thus  adapted  and  properly  trimmed,  anchor- 
age to  the  tooth  may  be  obtained  by  drilling  two  parallel  pits  into  the 
center  of  the  lingual  surface  on  each  side  of  the  pulp  (Fig.  248,  A),  just 
far  enough  to  insure  stability  in  the  attachment,  or  as  deep  as  possible 
without  encroaching  upon  the  latter  (Fig.  248,  B),  with  a  round  bur 
about  the  diameter  of  18  or  20  gauge  (B.  &  S.)  wire. 

The  plate  should  now  be  adjusted  to  position  and  perforated  with  a 


350 

small,  pointed  instrument  immediately  over  these  pits,  and  pins  made 
from  iridio-platinum  wire  of  the  same  size  as  the  bur  should  be  forced  to 
place  through  the  plate  and  into  the  pits  (Fig.  248,  C).  The  relation 
between,  pins  and  plate  should  now  be  temporarily  sustained  with  hard 
wax  or  temporary  stopping,  and  the  parts  then  carefully  removed  from 
the  tooth  and  invested,  using  only  enough  investment  material  to  cover 
the  pins  and  inside  of  plate.  When  the  investment  has  hardened  the  tem- 
porary medium  should  be  warmed  and  removed,  and  the  attachment  then 
well  reinforced. 

Since  it  is  obvious  that  much  of  the  stability  of 

Pins.  such  attachments  is  dependent  upon  the  integrity  of 

the  pins,  and  upon  their  close  adaptation  to  the  pits, 

the  latter  should  be  made  with  a  bur  of  a  diameter  about  the  same  as  that 


u 

Ficj.  249. 

of  the  wire  of  which  the  pins  are  made,  in  order  that  they  may  fit  closely, 
and  iridio-platinum  wire  should  be  used  because  of  its  strength. 

Instead  of  using  wire,  however,  a  stiff  and  even  more  accurate  fitting 
pin  may  be  made  by  tightly  packing  any  of  the  crystal  golds  into  the  pits 
after  perforating  the  plate,  and  with  it  in  position  until  they  are  com- 
pletely filled  and  the  gold  overlaps  the  perforations,  as  suggested  by  Dr. 
J.  E.  Keefe.  The  overlapping  of  the  gold  upon  the  plate  admits  of  the 
detachment  of  the  whole,  when  the  surface  should  be  slightly  reinforced 
with  solder,  without  investing,  in  which  procedure  the  pins  will  become 
so  filled  with  solder  as  to  render  them  stiff  and  solid,  after  which  the 
attachment  should  be  invested  and  the  necessary  additional  reinforcement 
then  given  to  the  whole  surface. 

Next  to  the  strength  of  the  pin,  the  stability  of 

Reinforcement.  such  an  attachment  will  depend  largely  upon  ade- 
quate reinforcement  and  stiffness.  While  22  or  20K. 
solder,  alone,  may  answer  this  purpose,  such  results  may  be  obtained  to 
the  best  advantage  ivhenever  the  plate  extends  around  to  cover  the 
approximal  surfaces  by  carefully  fitting  to  the  cervical  end  a  rim  of  clasp- 
metal  about  30  gauge  (Fig.  249,  A),  and  after  attaching  it  to  the  plate 
then  completing  the  reinforcement  over  the  entire  surface  as  uniformly  as 


351 

possible  with  a  solder  of  sufficiently  high  grade  to  preclude  subsequent 
re-fusion  in  the  final  assemblage  of  the  parts. 

It  has  been  recommended  that  the  entire  reinforcement  of  such 
attachments  be  made  by  laying  small  pieces  of  clasp-metal  over  the  sur- 
face, in  consecutive  layers,  and  uniting  them  with  solder  until  the  whole 
surface  is  flush  and  smooth  (Fig.  249,6),  which  may  be  done  with  or 
without  investing.  This  procedure  gives  a  uniform  thickness  and  a 
desired  stiffness  to  the  whole  attachment,  but  as  elasticity  and  stiffness  is 
required  mainly  at  the  cervical  end,  in  order  that  it  may  grasp  the  tooth 
firmly,  the  former  procedure  is  regarded  as  the  better  and  simpler  process. 

In  any  event  the  reinforcement  must  be  adequate  and  more  or  less 
uniform,  and  the  use  of  clasp-metal  is  imperative  as  a  means  of  impart- 


Ficj.  250 


ing  a  degree  of  strength  and  elasticity  such  as  is  not  to  be  obtained  by  the 
use  of  solder  alone.  When  such  reinforcement  has  been  made  the  attach- 
ment should  be  removed  from  the  investment,  cleaned  in  the  acid  bath, 
tried  to  position  upon  the  tooth  and  then  finished  to  the  point  of  polishing, 
as  usual. 


Groove  JlttacDments. 

Under  the  classification  of  groove  attachments  will  be  considered 
such  procedures  as  require  a  more  radical  preparation  of  the  natural 
crown  for  the  purpose  of  obtaining  increased  mechanical  fixation  of  the 
attachment. 

The  method  previously  described  as  the  "staple"  crown,  probably 
first  suggested  by  Dr.  Wilbur  F.  Litch  in  1888,  together  with  what  seems 
to  be  subsequent  modifications  of  the  original  principle,  as  have  been  sug- 
gested by  Dr.  C.  L.  Alexander,  of  Charlotte,  N.  C,  and  Dr.  J-  P.  Car- 
michael,  of  Milwaukee,  Wis.,  may  often  be  successfully  employed. 


352 

While   this    style    of    attachment    is    sometimes 
Indications.  recommended    as    being    applicable    to    almost    any 

tooth  in  the  arch,  a  conservative  employment  would 
seemingly  confine  its  use  mainly  to  the  cuspids  and  bicuspids,  or,  as  previ- 
ously mentioned,  to  those  teeth,  the  shape  and  normal  proportions  of 
which  are  favorable,  and  will  readily  admit  of  the  required  preparation. 

The  preparation   of  the  natural  crown   for  the 

Preparation  reception  of  such  an  attachment  comprises  cutting  a 

Of  natural  Crown,      groove  across  the  lingual  surface  of  the  six  anterior 

teeth  at  about  the  incisal  one-third   (Fig.  250,  A), 

and  then  root-wise  on  the  approximal  surfaces  to  a  close  proximity  with 

the  gum  line  (Fig.  250,  B). 


.2S/. 


These  grooves  form  the  mechanical  retention,  and  should  be  cut  just 
deep  enough  to  afford  a  secure  fixation  of  the  attachment  when  in  posi- 
tion, and  must  be  placed  in  such  relation  to  each  other  as  to  admit  of  the 
removal  of  the  piece  when  closely  adapted  to  them.  Also,  when  two  such 
attachments  are  to  be  used  in  one  structure,  the  requirements  of  parallel- 
ism must  be  closely  observed. 

Perhaps   the   most   ingenious   of   all   paralleling 
e»$lin'$  and  measuring  instruments  is  the  "Bridgeometer"  de- 

Brldgcomctcr.  ^j^^^  ^^  y)v.  L.  E.  Evslin,  of  Paris,  France. 

In  making  the  grooves  in  anterior  teeth,  if  adjacent  teeth  are  present, 
ample  separation  must  first  be  obtained,  and  it  should  then  be  noted  that 
the  occlusion  of  the  opposing  teeth  will,  or  is  made  to,  accommodate  the 
presence  of  the  attachment  when  in  position.  This  may,  of  course,  require 
either  that  the  lingual  surface  of  the  tooth  or  the  incisal  ends  of  the 


353 

opnosing  teeth  be  sufficiently  ground  to  affora  such  accommodation,  as 
previously  illustrated  in  Fig.  245. 

With  a  thin  knife-edge  stone  a  groove  should  now  be  cut  from  the 
mesial  to  the  distal  surface  at  about  the  point  indicated,  and  then  at  right 
angles  from  this  groove  the  approximal  grooves  should  be  formed  with 
a  short  cross-cut  fissure  bur. 

In  bicuspids  or  molars  ample  space  must  also  first  be  gained,  the 
Ungual  cusp  then  ground  down  to  afford  a  flat,  square  base  for  the  attach- 
ment, and  the  occlusal  groove  then  cut  up  close  to  the  buccal  cusps,  this 
to  be  followed  in  turn  by  the  cutting  of  the  approximal  grooves.  (Fig. 
251-) 


i 


Ficj.  252.  ^f'j-  253. 


While  these  attachments  are,  of  course,  more  or  less  applicable  to 
the  molar  and  incisor  teeth,  the  shapes  of  the  crowns  of  these  teeth 
are  usually  so  unfavorable  as  to  demand  considerable  mutilation  in  effect- 
ing the  required  preparation  for  an  accurate  adjustment,  and  indeed,  for 
this  reason  it  will  doubtless  be  found  that  the  process  will  most  often  be 
restricted  to  the  upper  cuspids. 

In   the   so-called   "staple"   or   "hood"   method  a 

Construction.  piece   of   round   platinum   wire,   about   18  gauge,   is 

first  closely  adapted  to  the  groove,  and  thin,  pure 
gold,  34  to  36  gauge,  then  burnished  over  this  and  trimmed  to  the  de- 
sired outline  of  the  crown.  The  two  are  then  removed,  and  the  wn-e 
"staple,"  remaining  in  the  depression  formed  in  the  gold  by  it,  is  attached 
with  solder,  after  which  it  may  be  invested  and  properly  reinforced. 
(Fig.  252.) 

In  the  so-called  "Carniichael  Attachment"  the  wire  staple  has  been 


354 

abandoned,  and  the  gold  is  burnished  directly  down  into  the  groove.  To 
prevent  tearing  and  to  facilitate  the  removal  of  the  gold  the  margins  of 
the  grooves  should  be  slightly  beveled.  A  ribbon  of  pure  gold  about  38 
gauge  should  be  placed  around  the  tooth  and  first  carefully  burnished  into 
the  grooves  with  a  suitable  instrument.  When  well  adapted  to  these 
points,  it  should  be  trimmed  and  carefully  adapted  to  the  entire  lingual 
and  approximal  surfaces,  as  described  in  the  former  method,  in  which 
the  procedure  may  be  facilitated  by  tying  it  to  the  tooth  with  a  ligature 
or  holding  it  securely  against  the  tooth  with  a  piece  of  tape. 

If  the  gold  is  perforated  in  being  adapted  to  the  grooves  such  places 
should  be  filled  in  with  any  of  the  crystal  golds,  and  when  the  adaptation 
is  thus  completed  the  attachment  should  be  carefully  removed. 

As  a  provision  against  the  possible  penetration  of  solder  to  the  under 
surface,  in  the  event  of  perforations,  it  is  well  to  paint  this  surface  with 
a  thin  coat  of  whiting  and  alcohol  just  previous  to  investing,  after  which 
the  attachment  should  be  reinforced  in  the  manner  previously  described 
in  connection  with  "plate  and  pin"  attachments.  While  this  may  be  done 
without  investing,  it  is  nevertheless  always  a  more  reliable  procedure, 
and  also  affords  opportunity  for  the  proper  adjustment  of  the  cervical 
rim  of  clasp-metal.  After  this  rim  is  attached  with  solder,  the  grooves 
should  be  filled  with  small  pieces  of  clasp-metal,  and  the  whole  then  uni- 
formly reinforced  with  a  grade  of  solder  which  will  not  be  re-fused  in 
the  final  assemblage  of  the  parts.  The  completed  attachment  and  its 
relation  to  the  supporting  tooth  is  shown  in  Fig.  253. 

While  fusible  metal  models  may  be  obtained  from  gutta-percha  or 
modeling  compound  impressions  of  the  tooth,  and  used  in  the  preliminary 
adaptation,  the  final  adaptation  should  always  be  done  directly  upon  the 
tooth  itself.  Such  attachment  may  also  be  made  by  casting,  using  clasp- 
metal,  as  suggested  by  Dr.  Taggart,  and  as  described  in  detail  in  con- 
nection with  inlay  work. 

Tnlay  Jfttacbntcnts. 

A  still  more  radical  method,  in  so  far  as  the  destruction  of  the  remain- 
ing crown  is  concerned,  is  involved  in  the  employment  of  various  forms 
of  "inlays"  as  attachments  for  the  support  of  bridges. 

In  view  of  the  apparent  tendency  toward  this  class  of  work,  particu- 
larly in  the  filling  of  teeth,  it  would  seem  that  such  attachments  are 
undoubtedly  destined  to  occupy  a  more  or  less  prominent  sphere  of  use- 
fulness, and,  indeed,  as  applied  to  supporting  small  bridges  of  two  or 
three  teeth,  or  to  supporting  one  end  of  even  more  extensive  pieces,  they 
may  often  be  used  with  every  assurance  of  success  and  permanency. 


355 

The    indications    for    the    use    of    this    class    of 
TndiC(ltion$.  attachments    usually    demands    a    more    extensive 

general,  in  proportion  as  the  condit'ons  may  seem 
favorable ;  and,  while  they  may  be  applied  to  almost  any  tooth  in  the  arch 
except  perhaps  the  lower  incisors,  they  are  more  readily  applicable  to 
pulpless  teeth ;  or  to  those  teeth  where  devitalization  of  the  pulp  for  the 
purpose  of  making  suitable  cavities  may  seem  warrantable,  or  where 
cavities  or  fallings  involving  the  approximal  surfaces  adjacent  to  the  miss- 
ing teeth  are  already  present. 

As    the    most    successful    application    of    such 

RCflUlretncntS.  attachments  may  be  regarded  as  being  more  or  less 

destruction  of  the  natural  crown  than  is  required  for 
any  other  similar  form  of  anchorage,  the  removal  of  the  pulp  is  usually 
necessary  as  a  means  of  properly  preparing  the  crown  for  the  reception 
of  an  inlay  which  may  not  only  be  properly  adapted,  but  which  may  also 
offer  sufificient  strength  to  insure  a  reasonable  degree  of  permanency. 

While  the  removal  of  the  pulp  in  anterior  teeth,  where  the  natural 
crown  is  to  be  preserved,  may  possibly  be  condemned  because  of  the  sub- 
sequent discoloration  which  may  result,  yet  such  a  discoloration  is  invari- 
ably the  fault  of  the  operator,  more  than  of  the  procedure,  and  may  usually 
be  avoided  if  the  proper  precautions  are  observed. 

In  molar  and  sometimes  in  bicuspid  teeth  having  crowns  of  good 
proportions^  however,  and  where  the  ravages  of  decay  have  already 
resulted  in  cavities  of  more  or  less  favorable  shape,  size  and  position,  ade- 
quate preparation  may  sometimes  be  obtained  without  encroaching  upon 
the  pulp  or  otherwise  exercising  an  influence  injurious  to  its  vitality. 

In  such  instances,  devitalization  may  not  be  necessary,  but,  as  the 
inlay  must  involve  the  contact  point  of  the  natural  croivn  to  such  extent 
as  to  bring  all  of  its  margins  to  a  self -cleansing  area,  and  must  then  be  of 
such  shape  as  to  be  mechanically  retained  in  the  cavity,  and  of  such  pro- 
portions as  will  insure  strength  in  its  attachment,  it  will  usually  be  found 
that  the  removal  of  the  pulp  is  either  advantageous  or  imperative. 

The  success  of  this  method  of  attachment  will 
Cavity  formation,  depend  largely  upon  cutting,  or  enlarging,  the  cavity 
until  it  involves  such  proportions  as  will  bring  all 
margins  to  a  self-cleansing  area — or  to  a  point  on  all  surfaces  beyond 
that  of  contact  with  the  adjacent  artificial  tooth  which  is  to  be  supported 
— and,  to  such  as  will  also  insure  adequate  mechanical  fixation  and 
strength  in  the  inlay. 

The  requirement  of  mechanical  fixation  demands  resistance  to  stress 
in  a  direction  tending  to  dislodge  it;  and  that  of  strength  demands  that 


356 

it  be  of  considerable  size.  Hence,  when  the  employment  of  this  method 
seems  indicated  conservation  of  tooth  structure  is  second  in  importance 
to  the  stability  and  permanency  of  the  attachment. 

Generally  speaking,  the  cavity  must  also  have  a  flat  base,  from 
which  the  axial  margins  should  be  trimmed  at  right  angles,  or  slightly 
diverging  toward  the  periphery.     It  should  then  be  free  from  vertical 


25a. 


undercuts  which  would  preclude  the  insertion  and  removal  of  the  inlay, 
and  have  smooth  definite  margins,  such  as  will  make  possible  and  insure 
a  close  and  accurate  adaptation. 

To  further  fortify  the  attachment  against  the  possibility  of  dislodg- 
ment  when  subjected  to  stress,  the  insertion  of  a  short,  stout  dowel  is 
recommended  wherever  possible.     If  the  depth  of  the  cavity  is  sufficient, 


Ficj.SSS 


and  its  formation  j)rovides  such  mechanical  resistance  to  stress  as  will 
preclude  dislodgment,  the  employment  of  a  dowel  is,  of  course,  not 
necessary,  yet  these  requirements  are  usually  best  met  by  its  use. 

Such  cavity  preparation  in  two  typical  classes  of  cases  involving  the 
linguo-approximal  surfaces  of  anterior  teeth,  and  the  approxinio-occlus:i. 
surfaces  of  posterior  teeth  is  illustrated  in  Fig.  254. 


35: 


When  the  cavity  has  been  thus  formed,  a  matrix 
Construction.  of  pure  gold  36  or  38  gauge   (or  of  platinum  foil 

i-iooo  if  preferred)  should  be  closely  adapted  to  all 
surfaces  and  margins.  This  may  be  accomplished  directly  in  the  cavity 
with  pledgets  of  cotton,  or  of  spunk,  and  suitable  burnishers.  Or,  an 
impression  may  be  taken  with  gutta-percha  or  cement ;  a  die  of  cement  or 
amalgam  made  from  this,  and  the  preliminary  adaptation  secured  by 
swaging  with  the  Brewster,  or  other  soft-rubber  plunger  swaging  devices, 
but  even  in  the  latter  method  the  final  adaptation  should  be  made  to  the 
cavity  itself. 

When  the  matrix  has  been  properly  adapted,  the  surplus  should  be 


Ficf.  E56. 

trimmed  away  until  only  a  narrow  margin  remains,  and  if  a  dowel  is  to 
be  employed  the  matrix  should  be  removed  and  the  cavity  at  this  time 
deepened  root-wise,  at  the  desired  point,  for  its  reception.  In  this,  care 
must  be  exercised  to  have  a  small,  stout  dowel  pass  but  a  short  distance 
into  the  pulp  chamber,  and  at  right  angles  with  the  floor  of  the  cavity,  so 
as  to  prevent  its  presence  from  interfering  with  the  removal  and  ready 
replacement  of  the  completed  inlay. 

The  matrix  should  now  be  filled  with  soft  wax  (because  of  its  easy 
removal  afterward)  to  preserve  its  shape  and  sustain  the  relation  between 
it  and  the  dowel ;  detached  from  the  tooth ;  invested,  and  subsequently 
filled  to  the  desired  contour,  first  with  globules  of  scrap  gold,  and  then 
with  22  k.  solder,  after  the  investment  has  become  hard  and  the  wax 
removed. 

While  the  best  results  are  doubtless  to  be  obtained  from  the  use  of 
pure  gold  of  the  gauge  mentioned  for  the  matrix,  and  by  contouring  in 


358 

this  manner,  some  prefer  to  use  platinum  foil.  The  extreme  thinness  of 
the  latter  diminishes  the  work  incident  to  the  final  finishing  upon  the 
tooth,  but  increases  the  tendency  to  become  distorted  in  shape  in  remov- 
ing- and  investing.  To  prevent  the  latter,  Dr.  C.  C.  Allen,  of  Kansas 
City,  has  suggested  filling  the  matrix  before  removing  with  gum  cam- 
phor, which  may  be  burned  out  easily  after  investing,  or  a  medium  hard 
wax  may  be  used,  for  the  same  reason.  The  adjustment  of  an  ordinary 
circular  matrix  to  restore  the  approximal  wall,  and  the  filling  of  the 
entire  matrix  for  the  inlay  with  crystal  gold  previous  to  subsequently 
investing  and  finishing  with  solder,  is  also  recommended  and  may  be 
found  useful  in  some  cases. 


Caggart's  mctbod  of  Casting. 

A  method  of  constructing  gold  inlays  which  reduces  the  procedure 
to  a  system  of  scientific  mechanics,  and  which  is  so  simple,  expeditious, 
certain  and  accurate  as  to  seem  destined  to  practically  supersede  afi 
former  methods  of  making  large  restorations,  has  been  devised  by  Dr. 
W.  H.  Taggart,  of  Chicago. 

In  this  process  the  inlay  is  made  by  casting,  and  for  the  reason  that 
gold  inlays  which  are  to  be  used  as  attachments  for  bridgework  must 
usually  be  large,  and  always  accurately  adapted  to  the  cavity,  and  to  the 
occlusion,  the  method  seems  particularly  applicable,  and  quite  ideal. 
The  possibility  of  using  pure  or  high-grade  gold  also  allows  more  free- 
dom in  soldering. 

In   the    procedure,    when    the    cavity    has    been 

Procedure.  prepared  in  accordance  with  all  of  the  requirements 

it  is  coatefl  with  liquid  vaseline  and  filled  with  a 
special  rlark  colored  zva.r,  into  which  the  patient  is  required  to  bite. 
This  forces  the  wax  well  down  into  the  cavity,  and  conforms  it  to  ac- 
commodate the  occlusion.  It  is  chilled  with  a  spray  of  cold  water,  and 
then  slightly  loosened,  or  unseated,  with  a  pointed  instrument,  after 
which  the  patient  is  again  requested  to  bite,  thus  firmly  forcing  it  back 
into  place. 

The    wax    is    now    again    cliillcd,    carefully    re- 
Tormlng  moved  with  a  pointed  instrument,  and  trimmed  and 

max  Tllllnfl.  carved  to  the  desired  outline  of  the  completed  fill- 

ing, during  which  it  may  be  replaced  in  the  cavity 
from  time  to  time,  but  must  be  handled  gently,  and  kept  at  a  suitable 
temperature  by  means  of  di])ping  in  cold  water.  It  is  also  necessary 
to  keep  the  cavity,  instruments  and  fingers  perfectly  clean  during  this 


359 

procedure  in  order  to  preclude  the  presence  of  foreign  substance  in  the 
wax. 

When  the  wax  filHng  has  been  thus  formed  and  trimmed,  it  should 
be  replaced  in  the  cavity,  and  all  overhanging  edges  carefully  removed 
and  the  adaptation  to  the  margins  perfected.  This  may  be  done  by 
coating  a  strip  of  the  thinnest  tape  with  vaseline  and  drawing  it  back- 
ward and  forward  over  the  approximal  and  cervical  margins,  in  much 
the  same  manner  as  a  finishing  strip  is  used,  and  then  by  wiping  over 
the  occlusal  margins  with  a  pledget  of  cotton  also  dipped  in  vaseline. 

This  technique  is  important  in  every  detail  and  must  be  closely  ob- 
served, as  the  slightest  imperfections  will  be  reproduced  in  the  gold, 
and,  therefore,  the  finished  filling  can  not  be  any  more  perfect  than  the 
wax  one. 

The  wax  used  is  a  composition  of  wax  and  parafin,  thoroughly 
filtered  in  order  to  be  free  from  foreign  substances. 

When    the    wax    filling    is    thus    finished    it    is 
TltDCSting.  chilled,  carefully  removed  and  immediately  invested. 

In  the  latter  procedure  one  end  of  a  piece  of  round 
wire,  about  12  to  14  gauge,  which  is  to  be  used  as  a  sprue-former,  is 
slightly  heated  and  then  gently  attached  to  the  center  of  the  wax,  after 
which  a  small  quantity  of  a  special  investment  material  is  mixed  and 
then  carefully  packed  into,  over  and  around  it  until  the  entire  filling  is 
completely  submerged,  with  the  exception  of  the  end  of  the  sprue-former, 
by  which  it  has  been  held  with  the  fingers. 

This  preliminary  investment  is  thus  made  in  order  to  prevent  air 
spaces  adjacent  to  the  wax,  and  when  it  has  crystallized  the  whole  is 
finally  invested  in  the  casting  flask. 

The  latter  is  a  heavy  brass  ring  which  engages  in  a  flat  base,  having 
an  elevation  in  the  center  and  a  perforation  in  the  center  of  this  ele- 
vation. 

The   exposed   end   of  the   sprue-former  is  now 
Tiasking.  inserted  in  the  perforation  in  the  base  of  the  flask, 

the  ring  adjusted  to  position  thereon,  and  the  whole 
then  filled  with  investment  material.  After  crystalization  the  base  is  re- 
moved and  the  sprue-former  gently  pulled  out.  This  leaves  a  depression, 
or  crucible,  formed  by  the  elevation,  and  a  channel  leading  from  it  to 
the  wax.  formed  by  the  sprue,  and  a  mould  of  the  wax  filling,  all  com- 
bined in  one  piece. 

The    mould    is    now    placed    over    the    Runsen- 

£a$tin9.  burner  and   slowly   heated  until  the   wax  is   burned 

out  and  absorbed  by  the  investment  material,  after 


36o 

which  it  is  thoroughly  dried  and  heated,  and  then  transferred  to  an  in- 
genious automatic  machine,  which,  among  other  features,  embraces  a 
small  oxy-hydrogen  blow-pipe. 

An  ingot  of  pure,  22  k.,  or  coin  gold  is  now  placed  in  the  crucible 
and  fused.  When  carried  to  a  degree  considerably  beyond  the  melting 
point,  a  lever  which  automatically  cuts  off  the  flame  and  hermetically 
closes  the  top  of  the  mould,  is  operated,  and  the  melted  gold  is  simul- 
taneously forced  into  the  mould  by  the  pressure  from  the  gas  cylinder. 

When  the  casting  is  made,  the  flask  is  removed  and  plunged  into 
cold  water,  after  which  the  stem  of  surplus  gold  is  separated  with  a 
small  saw  and  the  filling  finished.  A'ery  little  finishing  is  required,  and 
the  result  is  an  accurate  reproduction  of  the  wax,  however  perfect  or 
imperfect  it  may  have  been. 

The   so-called   "hollow"   inlays,    or  any   irregu- 

Uariations.  larities   of   the   cavity   surfaces    for   the   purpose   of 

facilitating  anchorage  to  the  tooth,  may  be  made  by 
carving  the  wax  ;  and  "pins"  or  "posts"  may  also  be  provided  by  first 
fitting  them  to  the  cavity,  with  as  much  surplus  as  occlusion  and  contour 
will  admit,  and  allowing  them  to  become  a  part  of  the  wax  filling,  using 
clasp  gold  or  iridio-platinum  wire  of  the  desired  size.  These  are  held 
securely  in  the  investment  and  subsequently  become  an  integral  part  of 
the  casting. 

This   method   is   not   only   applicable  to   inlays, 
General  but  to  backings  for  all  forms  of  diatoric  or  replace- 

JJppllcation.  able   teeth,   to   caps    for   crowns,   and   to   removable 

bridges  and  even  partial  dentures ;  and  25  per  cent, 
platinum  solder,  clasp-metal,  or  any  of  the  alloys  of  gold,  or  even  silver 
or  copper  may  be  used.  Indeed,  its  application  seems  practically  un- 
limited, and  to  be  restricted  only  by  the  requirements  of  a  suitable  in- 
vestment material,  and  the  size  of  the  flask,  which  future  development 
will  doubtless  afford. 

When  the  construction  of  the  inlay  by  either  of 
Tinal  Requirements,  these  methods  has  been  completed,  it  should  be 
l)laced  in  position  in  the  cavity  and  finished  with 
stones  and  di^ks  until  the  desired  adaptation  and  a  proper  occlusion 
has  been  obtained,  when  the  final  "bite"  and  impression  should  be  taken. 
The  completed  inlays  for  the  typical  cavities  previously  illustrated  are 
shown  in  Fig.  255. 

A  class  of  cases  in  which  molar  teeth  have  tipped  forward  until  their 
occlusion  is  destroyed,  which  are  encountered  frequently,  and  particularly 
in  the  lower  arch,  and  to  which  this  method  of  attachment  is  especially 


36i 

applicable  as  a  means  of  affording  anchorage  for  a  bridge,  and  at  the 
same  time  of  restoring  the  occlusion,  is  illustrated  in  Fig.  256. 

Another  class  of  cases  involving  the  employment  of  the  "inlay" 
attachment  on  the  posterior  end,  in  conjunction  with  the  "plate  and  pin" 
attachment  on  the  anterior  end,  is  illustrated  in  Fig.'  257.    The  application 


yT^^TRi! 


Fiq  .  257. 

of  each  attachment  in  its  respective  place  is  typical,  and,  next  to  full 
crowns,  this  is  regarded  as  being  one  of  the  best,  most  practical  and 
highly  artistic  means  of  supplying  missing  bicuspids. 

Cclescopc  jittdcbments. 

The  telescope  attachment  is  sometimes  employed  upon  the  molar 
and  bicuspid  teeth  in  the  shape  of  partial  gold  crowns,  involving  only  the 
occlusal  one-half  or  two-thirds  of  the  natural  crown. 


362 

While    this    method    requires    hut    a    minimum 
Tnd]cation$.  of    cutting    of    the    natural    crown,     and    may    be 

useful  in  instances  where  the  attachment  is  not  con- 
spicuously visible,  where  the  teeth  so  employed  stand  alone,  and  without 
opposition  from  occluding  teeth,  in  the  arch,  or  where  only  a  more  or  less 
temporary  structure  is  required,  still  at  best  they  are  indicated  as  an  expe- 
diency rather  than  as  a  general  practice. 

As  they  are  not  intended  to  pass  beyond  the  most  bulbous  portion 
of  the  natural  crown,  about  the  only  preparation  necessary  to  their  ad- 
justment is  the  removal  of  enough  of  the  occlusal  surface  to  admit  of 
cusps  of  sufficient  thickness  to  withstand  any  stress  of  mastication  to 
which  they  may  be  subjected. 

For  this  reason  their  employment  is  usually  confined  to  teeth  having 
vital  pulps  and  where  it  seems  desirable  to  preserve  this  vitality,  for,  if 
the  pulp  should  or  may  be  sacrificed,  there  would  be  no  apparent  reason 
for  not  properly  preparing  all  surfaces  of  the  natural  tooth  and  adjusting 
the  usual  style  of  artificial  crown  to  it. 

Hence  the  use  of  such  an  attachment  can  only  be  regarded  as  a  means 
to  an  end,  and  the  end  is  to  save  the  pulp ;  but  if  a  fixed  bridge  is  indi- 
cated at  all,  this  objective  point  is  secondary  to  its  fixation  in  the  most 
secure  and  permanent  manner  possible. 

On  the  other  hand,  however,  they  may  be  useful 

Possible  as  a  means  of  supplying  missing  teeth  in  the  mouths 

Objections.  of  very  young  patients,  where,  because  of  the  lack 

of  root  development,  it  may  not  seem  warrantable  to 

devitalize  the  pulp  or  to  subject  the  tooth  to  the  shock  of  more  extensive 

preparation  such  as  would  be  indicated  for  a  complete  crown. 

In  these  instances  such  attachments  would  be  expected  to  serve,  in 
the  main,  but  a  temporary  purpose,  and  thus  only  defer  a  more  perma- 
nent procedure  until  a  more  favorable  time. 

Whenever    indicated    this    style    of    attachment, 
Construction.         which  is  illustrated  on  the  molar  teeth  in  conjunction 
tion   with   "inlay"   attachments  on  the  bicuspids,  in 
Fig.  258,  should  be  constructed  in  accordance  with  the  general  require- 
ments previously  outlined  for  a  full  crown,  except,  of  course,  that  any 
peripheral  preparation  of  the  natural  crown  is  unnecessary. 

For  prophylactic  reasons  it  should  be  observed,  however,  that  the  sur- 
face of  the  attachment  which  approximates  the  adjacent  artificial  tooth 
be  allowed  to  extend  sufficiently  far  beneath  the  contact  point  with  the 
latter,  so  as  to  leave  a  free  interproximal  space,  and  thus  make  it  more  or 
less  self-cleansing.     (See  Fig.  258.) 


3^3 

Ccmporarv  Jlttacbmcnts. 

Incident  to  the  correction  of  irregularities  of  the  teeth,  the  modern 
scientific  practice  of  orthodontia  and  the  recognized  importance  of  a  full 
complement  of  teeth  in  the  restoration  or  preservation  of  the  normal 
occlusion,  not  infrequently  demands  the  application  of  some  form  of  den- 
tal bridgework  to  the  mouths  of  young  patients,  as  a  means  of  supplying 
missing  teeth,  and  of,  perhaps,  temporarily,  but  securely,  retaining  the 
natural  teeth  in  their  proper  position. 

The  exigencies  and  varied  requirements  of  such 
Tndications.  cases,  together  with  the  unfavorable  age  of  the  pa- 

tient,   usually    indicates    the    employment    of    appli- 
ances   which    may    be    securely    "fixed"    to    the    supporting    teeth,    and 


F/(/.  S58. 


yet  in  the  mouths  of  patients  under  fourteen  or  fifteen  years  of  age  no 
efifort  toward  a  radical  procedure  which  would  materially  mutilate  the 
natural  teeth  is  usually  indicated  or  should  be  attempted,  because  of  the 
more  or  less  imperfect  development  of  the  roots,  and  of  the  difficulties 
otherwise  involved  in  the  procedure. 

In  such  cases  the  missing  teeth  should  usually  be  supplied  in  the 
most  simple  manner  possible  until  such  time,  at  least,  as  the  environment 
and  conditions  may  be  more  favorable  for  securing  a  greater  degree  of 
permanency. 

Up  to  the  age  of  perhaps  fifteen  or  sixteen,  this  would  usually  indi- 
cate the  employment  of  simple  bands  as  a  means  of  attachment  for  the 
support  of  artificial  teeth,  and  in  their  application  care  should  be  exercised 
to  avoid  any  shock  to  the  pulps  of  the  teeth  so  employed,  and  to  place 
such  bands  around  the  natural  crowns  at  their  largest  circumference  in 
order  that  no  possible  mechanical  irritation  may  result. 


364 

In  the  application  of  such  bands  about  32  gauge 

Jlpplication.  22  karat  gold  should  be  used,  and  in  the  adaptation 

to  the  anterior  teeth  the  exposed  labial  portion  may 

be  made  extremely  narrow,  but  the  lingual  portion  should  cover  enough  of 

the  natural  crown  to  admit  of  the  use  of  a  sufhcient  quantity  of  cement  in 


Fiq.  259. 


Fiq.  260 


mounting  to  insure  a  degree  of  stability  in  the  attachment  which   will 
prevent  its  being  forced  rootwise,  or  otherwise  displaced  (Fig.  259). 

On  the  posterior  teeth,  however,  a  further  precaution  against  such  dis- 
placement should  be  observed  by  the  addition  of  an  occlusal  rest  as  a  part 
of  the  liand  (Fig.  260).  In  the  event  of  the  latter  interfering  with  the 
occlusion  accommodation  must  be  made  by  grinding  the  tooth  at  these 
points,  or  else  the  opposing  teeth. 


365 

Appliances  of  this  character  are  of  course  only  temporary  in  nature, 
but  when  properly  adapted  and  securely  mounted  with  cement,  they  may 
support  one  or  two  teeth,  and  thus  serve  the  desired  purpose,  until  such 
time  as  a  more  radical  preparation,  and  more  permanent  method  of  fixa- 
tion, may  be  indicated. 

While  removable  appliances  may  be  empbyed  in  such  cases,  they  are 
not  so  reliable,  and  are  not  usually  to  be  recommended,  because  of  the  dif- 
ficulty of  learning  to  wear  them  ;  of  the  tendency  to  forget,  misplace  or  lose 
them,  or  of  the  possibility  of  swallowing  them. 

Occlusal  and  Lingual  Supports. 

While  it  is  quite  logical  to  suppose  that  attachments  for  bridges 
which  are  to  be  securely  anchored  to  the  teeth  must,  of  necessity,  be  more 
or  less  permanently  fixed  in  their  relation  to  the  supporting  natural 
crowms,  there  are  nevertheless  instances  where  a  simple  rest  or  support 
may  be  found  exceedingly  useful,  and  where  the  judicious  employment 
of  such  rest  will  answer  practically  the  same  purpose,  as  far  as  the  re- 
quirements are  concerned,  as  would  any  of  the  preceding  methods  of 
attachment. 

This  is  particularly  true  of  a  style  of  support 
Occlusal  Supports,      which,  because  of  being  applicable  mainly  to  the  pos- 
terior teeth,  and  of  then  involving  only  the  approx- 
imal  and  occlusal  surfaces  of  the  natural  crown,  may  be  properly  desig- 
nated as  "occlusal"  supports. 

As  there  is  a  marked  line  of  distinction  between 

Tndkations.  anchorage  and  support,  and  as  all  fixed  bridges  must 

be  securely  "anchored,"  the  "judicious  employment" 

of  any  style  of  "support"  would  necessarily  mean  that  it  could  be  used 

ojily  in  conjunction  w^ith  one  or  more  other  methods  of  "anchorage"  or 

attachment. 

Hence,  in  small  bridges  where  but  one  or  two  teeth  are  to  be  sup- 
plied, and  where  any  of  the  preceding  methods  of  attachment  are  used  as 
the  anchorage  for  one  end,  if  the  strength  and  stability  of  the  attachment 
itself  seems  adequate  to  the  requirements  of  anchorage,  a  simple  support 
on  the  other  end  may  be  all  that  is  required  to  insure  reasonable  perma- 
nency in  the  structure. 

Also,  in  more  extensive  bridges  involving  tzvo  or  more  attachments, 
which  seem  to  ofifer  a  stability  adequate  to  the  requirements,  and  yet 
where  it  may  be  desirable  to  extend  one,  or  in  some  exceptional  instances 
/•ei'o,  teeth,  either  anterior  or  posterior  to  one  of  the  attachments,  a  simple 
support  may  answer  for  the  extreme  end  of  the  extension. 


366 

Such   a  support   may  be   obtained,   when   indi- 
Hpplication.  cated,  in  a  manner  which  will  require  but  compara- 

tively little  destruction  of  the  natural  crown  thus 
used,  and  yet  which  will  afford  adequate  resistance  to  lateral  and  vertical 
stress,  and  at  the  same  time  produce  a  cosmetic  effect,  by  making  or 
utilizing  a  cavity  in  the  approximo-occlusal  surface  of  the  natural  crown 


f/^.ES/, 


(Fig.  261,  A)  ;  filling  and  finishing  it  in  a  permanent  manner  first  (Fig. 
261,  B),  and  then  cutting  a  seat  in  the  center  of  the  filling  which  will  offer 
accommodation  for  the  end  of  a  suitable  bar  projecting  from  and  forming 
a  part  of  the  bridge  (Fig.  261,  C). 

For  prophylactic  reasons  such  a  cavity  must  be  extended  sufficiently 
far  so  as  to  bring  its  margins  to  immune  areas,  and  to  such  proportions 
as  to  admit  of  the  subsequent  cutting  of  a  seat  in  the  filling  which  will 
not  involve  any  of  the  margins,  and  yet  which  will  receive  the  project- 
ing end  of  a  square  iridio-platinum  wire  about  16  gauge.  When  the  fill- 
ing is  inserted,  finished  and  polished,  the  seat  may  be  cut  in  it  with  a  cross- 
cut fissure  bur  of  the  same  diameter  as  the  wire  to  be  used.  This  should 
be  done  after  the  other  attachment,  or  attachments,  is,  or  are,  made,  and 
then  with  them  in  position  the  wire  should  be  fitted  into  the  seat  and 


3^7 
allowed  to  extend  over  until  its  other  end  rests  against  the  attachment. 
When  the  proper  relation  is  thus  secured  and  insured  the  final  "bite"  and 
impression  may  be  taken. 

Dr.  Ottolengui  advocates  the  following  method  of  constructing  an 
occlusal  rest.  A  filling  is  made  and  finished  first,  as  already  described. 
The  slot  or  seat  is  then  cut  and  is  constructed  with  a  flat  bottom  and  very 
slightly  flaring  sides.  Into  this  slot  is  then  burnished  a  piece  of  thin 
pure  gold  which  is  brought  into  a  close  adaptation  with  a  smooth  flat  end 
burnisher  and  a  mallet.  This  gold  is  also  carried  over  and  burnished 
against  the  approximal  surface  of  the  filling  extending  slightly  below  the 


Fiij.  262. 


contact  point.  Into  this  is  then  fitted  the  iridio-platinum  square  post,  the 
two  waxed  together,  removed,  invested  and  united  with  20  karat  solder. 
This  is  then  returned  to  the  mouth  and  fitted  and  soldered  to  the  attach- 
ment, as  already  described  in  connection  with  the  simple  bar.  The  ad- 
vantages claimed  bv  Dr.  Ottolengui  are  a  more  firmly  setting  rest,  which 
not  only  makes  a  cleaner  appliance,  but  being  burnished  also  against  the 
approximal  surface,  may  be  made  to  serve  slightly  as  a  lock,  the  finished 
piece  snapping  into  place.  The  final  finishing  of  the  occlusal  rest  should 
be  made  with  the  piece  in  the  mouth,  so  as  to  make  it  continuous  with  the 
filling  in  which  it  rests,  and  thus  smooth  to  the  tongue. 

This  projecting  end  need  only  rest  firmly  and  snugly  in  position  in 
the  filling,  and  no  effort  should  be  made  to  attach  it  more  securely  than  is 
thus  to  be  obtained  by  such  a  fit.  Indeed,  if  the  fit  of  the  projecting  end 
of  the  wire  into  the  seat  in  the  filling  is  at  all  close  it  will  rest  quite 
firmly  therein,  thus  supporting  that  end  of  the  bridge  against  vertical  and 
lateral  stress,  and  the  slight  degree  of  mobility  afforded  will  be  found  ad- 


368 

vantageous  instead  of  objectionable.  When  used  to  support  two  teeth, 
however,  where  the  leverage  is  so  appreciably  increased,  it  is  usually  a  safe 
precaution  against  the  possibility  of  loosening  the  attachment  at  the  other 
end,  to  warn  the  patient  to  avoid  the  constant  or  too  frequent  use  of  hard, 
sticky  substances. 

While  the  advantages  to  be  obtained  from  the  employment  of  such 
a  support  are  quite  sufficient  to  even  warrant  the  cutting  of  cavities  in 
sound  teeth,  still  the  method  is  more  particularly  applicable  when  a  cavity 
already  presents.  The  typical  application  of  this  principle  to  the  support 
of  the  posterior  end  of  small  bridges  which  are  otherwise  securely  an- 
chored, is  illustrated  in  Fig.  262. 


F/a.  263, 
I 

The  former  practice  of  extending  projecting  bars  into  cavities  and  of 
subsequently  inserting  the  filling  over  and  around  them  after  mounting 
the  bridge,  has  practically  been  abandoned,  because  of  the  extreme  diffi- 
culty of  making  a  permanent  filling  under  such  conditions,  and  of  the  con- 
sequently temporary  nature  of  attachments  made  in  this  or  a  similar 
manner. 

In  a  preceding  consideration  of  the  underlying 
£insual  principles  particular  attention  has  been  called  to  the 

Supports.  necessity   for  employing  some  mechanical  means  of 

overcoming  leverage  where  one  tooth  is  to  be  sus- 
pended from  another,  and  of  thus  preventing  rotation  of  the  supporting 
tooth  on  its  long  axis. 

In  so  far  as  concerns  the  application  of  this  principle  to  the  construc- 
tion of  such  bridges  anterior  to  the  second  bicuspid  this  may  be  accom- 
plished by  the  employment  of  what  may  be  designated  as  a  lingual 
support. 

The  indications  for  the  employment  of  such  sup- 
Tndications.  jjorts  arc  general  as  applied  to  the  construction  of 

bridges  where  a  single  t(K)lh  is  sus])C'n(lc(l  from  a 
single  attachment,  anywhere  anterior  to  and  including  tlie  second  bicus- 
pid, for  the  reason  that  the  roots  of  the  nicisors,  cuspids  and  bicuspids 


369 

are  of  more  less  conical  slispe,  and,  hence,  unless  fortified  against  rota- 
tion, will  invariably  succumb  to  the  power  of  the  lever,  and  ultimately 
become  so  twisted  on  their  long  axis  as  to  result  in  the  presentation  of  a 
space  between  the  suspended  artificial  tooth  and  the  adjacent  natural 
tooth,  much  as  a  gate  swings  on  its  hinge  from  the  direction  in  which 
the  force  is  applied,  and  as  is  illustrated  in  Fig.  263. 

In  the  application   of   such   supports,   however, 
Application.  their    practicability    or    impracticability    will    depend 

largely  upon  the  following  conditions :  First,  an  ad- 
justment which  will  not  interfere  with  the  occlusion  of  the  opposing  teeth, 


/vy.  £S^. 


nor  impinge  upon  the  soft  tissues ;  second,  an  adjustment  which  will  be 
sufficiently  free  from  contact  to  maintain  as  nearly  a  sclf-clcansiiig 
space  bctivccn  it  and  the  tooth  and  gum  as  possible;  third,  an  adjustment 
which  will  afford  only  a  miniintim  contact  with  the  tooth  against  which  it 
rests,  and  fourth,  the  possession  of  sufficient  rigidity  to  withstand  the 
stress  imposed  (Fig.  264). 

If  these  requirements  are  observed  stich  supports  need  not  afford 
much,  if  any,  opportunity  for  the  occurrence  of  caries  at  their  point  of 
contact  with  the  natural  crown  ;  need  not  be  appreciably  unhygienic,  nor 
an  impediment  to  the  movements  of  the  tongue,  nor  to  speech. 

In  order  that  they  may  possess  sufficient  rigidity  and  strength,  noth- 
ing smaller  than  16  gauge  round  iridio-platinum  wire  should  be  used,  and 
the  adjustment  may  be  made  upon  the  model  before  the  case  is  invested, 
or  after  it  is  invested  if  the  following  precaution  is  observed.  When  the 
anchor  attachment  and  dummy  are  completed  and  they  are  ready  to  be 


370 

'iivested  and  united,  the  proper  relation  should  be  sustained  with  hard 
wax.  A  small  quantity  of  soft  wax  should  then  be  attached  to  the  lingual 
surfaces  of  the  pieces  and  pressed  against  the  same  surface  of  the  adjacent 
tooth  on  the  model.  This  will  afford  an  impression  of  this  surface  of  the 
tooth,  so  that  when  the  case  is  detached  from  the  model  and  invested, 
and  the  wax  is  removed,  an  accurate  outline  of  this  surface  of  the  tooth 
against  which  the  support  is  to  rest,  will  present  in  the  investment. 


Fi<j.  265. 


The  support  may  then  be  adjusted,  as  indicated,  placed  in  position, 
and  the  case  heated  and  soldered. 

In  finishing,  the  end  of  the  support  should  be  nicely  rounded  down 
toward  the  tooth  upon  which  it  is  to  rest,  and  before  mounting  it  should 
be  observed  that  it  offers  no  interference  to  the  occlusion,  and  no  unnec- 
essary obstruction  to  the  tongue. 

The  application  of  this  class  of  supports  showing  their  correct  rela- 
tion and  possible  effectiveness  in  such  typical  cases,  for  example,  as  a 
second  bicuspid  supporting  a  first  bicuspid,  and  a  central  supporting  a  lat- 
eral, is  illustrated  in  Fig.  265. 


Application  and  Construction  of  Dummies, 


CHAPTER  XXI. 

Application  and  Construction  of  Dummies  :   Anterior  Dummie  ;    Selection  of  Facings, 
Adaptation,    Backing.      Artificial    Restoration    of    Gum.      Posterior    Dummies; 
Porcelain  Faced  Bicuspids  and  IMolars;   xApplication,   Selection  of  Facings, 
Backing,  Occlusion,   Carved  Cusps,  Attaching  Facing  and  Cusps,  Con- 
tinuous Cusps,   Die-Plate  Cusps.     All-Gold  Dummies;   Indications, 
Construction.      Occlusal    Surface   Dummies;    Indications,    Con- 
struction.    Lateral  Gravitation  :  Correction  of  IMalposition, 
"Attachment"   and   "Dummy"   Combined.     Opening  of 
the  "Bite"  :  Elongation,  Abrasion,  Typical  Application. 


An  effort  toward  a  systematic  presentation  of  the  various  methods 
of  "attachment"  and  "support"  for  "fixed"  bridgework,  is  necessarily  fol- 
lowed by  a  consideration  of  the  construction  and  employment  of  the 
"dummies"  which  are  to  be  attached  thereto,  and  which  are  to  act  as 
substitutes  for  missing  teeth,  thus,  in  a  general  way,  forming  the  "body" 
of  the  bridge. 

In  the  development  of  this  class  of  work  any  number  of  designs  of 
artificial  teeth  have  been  introduced,  but  only  a  few  are,  at  the  present 
time,  regarded  as  applicable,  and  more  or  less  generally  applicable. 

Jlittcrior  ''Dummies/* 

In  supplying  missing  teeth  anterior  to,  and  often  including  the  first 
bicuspid  (where  an  occhtsal  surface  is  seldom  required),  the  ordinary 
long-pin,  "flat-back"  facing,  is  generally  used. 

In  the  construction  of  bridges  involving  anterior 

Selection  teeth,  the  facings  which  are  to  substitute  the  missing 

Of  Tacings.  teeth  should  be  selected  as  soon  as  the  final  model 

with  the  "attachments"  in  place,  has  been  secured. 


Z72 

(Fig.  266.)  In  their  selection  it  should  be  observed,  first,  that  they  fill 
the  space  between  the  attachments ;  second,  that  they  are  as  nearly  as  pos- 
sible proportionate  in  size,  as  to  length  and  width,  with  the  crowns  of  the 
remaining  natural  anterior  teeth  not  included  in  the  bridge ;  and  tJiird, 
that  the  color  closely  resembles  that  of  the  natural  teeth.  In  this  latter 
connection  it  must  be  remembered  that  the  presence  of  the  metal  backing^ 
always  darkens  the  shade  of  the  facing,  and  also,  that  in  the  event  of  no<- 


/vy.  2&6. 


being  able  to  perfectly  match  the  shade,  one  slightly  darker  is  invariably 
preferable  to  one  the  least  bit  lighter.  It  is  also  well  to  consider  the  varia- 
tions in  the  shade  of  the  natural  teeth  in  the  same  mouth,  as  previously 
mentioned,  and  to  make  the  selection  accordingly. 

As  soon  as  the  desired  selection  has  been  made,  a 

Adaptation.  small  roll  (jf  soft  wax  should  be  sealed  to  the  model, 

and   tlic   facings  then  ground  until  their  necks  are 

perfectly  fitted  to  the  gum,  and  then  until  they  nicely  fill  the  space  without 


373 

being  in  absolute  contact  with  each  other.  The  latter  requirement  is  nec- 
essary as  a  means  of  preventing  impingment  from  the  shrinkage  of  the 
solder  in  assembling,  which  if  not  observed,  might  result  in  fracturing  the 
porcelain. 

When  the  neck  of  the  facing  has  been  closely  adapted  to  the  outline 
of  the  model,  the  extreme  edge  should  always  be  rounded  until  blunt  and 
smooth,  in  order  that  no  irritation  to  the  soft  tissue  may  thereby  be  of- 
fered. 


Iziq.  267. 


As  it  is  necessary  for  cosmetic  and  hygienic  reasons  that  the  end  of 
the  facing  should  rest  in  direct  contact  with  the  gum,  this  feature  must 
be  observed,  or  inflammation  and  often  hypertrophy  will  result. 

When  these  requirements  have  been  observed  the 
Backing.  incisal  or  occlusal  end  of  the  facings  should  be  bev- 

eled to  a  more  or  less  thin  edge,  and  a  double,  or 
otherwise  well  reinforced  backing  then  adapted  in  accordance  with  the 
requirements  in  this  connection,  as  previously  outlined  for  single  crowns, 
except  that  the  backing  should  never  extend  to  the  extreme  cervical  end, 
nor  be  allowed  to  interfere  with  the  direct  adaptation  of  this  end  of  the 
facing  to  the  gum.     (Fig.  267.) 

When  allowed  to  project  beyond  the  cervical  shoulder  on  the  facing, 
its  presence  offers  no  protection  to  the  porcelain,  but  only  interferes  with 
the  accuracy  of  the  desired  adaptation  to  the  gum,  and.  unless  amply  rein- 
forced, would  be  likely  to  draw  away  from  the  porcelain  and  thus  produce 
a  joint  or  pocket  for  the  accumulation  of  secretions  which  would  be  de- 
cidedly unhygienic. 

When  double,  or  well  and  otherwise  uniformly  reinforced  backings 
are  thus  adapted  and  securely  retained  to  the  porcelain  by  bending  the 
pins,  they  should  be  separately  finished  with  files  or  stones,  and  then,  even 
with  fine  disks  to  the  point  of  polishing,  in  order  to  preclude  the  possibility 
of  overhanging"  edges. 


374 


It  has  already  been  observed  that,  for  cosmetic 
reasons,  tJie  artificial  tooth  should  akvays  be  of  the 
same  exact  length  as  the  crozvns  of  the  adjacent  or 
corresponding  natural  teeth,  yet  the  excessive  ab- 
fouiid  to  exist  where  bridgework  is  indicated  often 
prechides  this,  or  demands  the  special  preparation  of  facings,  or  the  em- 
ployment of  gum-block  teeth. 


Hrtificial  Restoration 
of  Gum. 

sorption  frequently 


a. 


Fiq.  268. 


While  gum-block,  long-pin  teeth  may  sometimes  be  selected,  properly 
ground  and  used  to  good  advantage  in  this  class  of  cases,  still  the  demand 
for  them  is  not  great  enough  to  warrant  their  being  manufactured  in 
large  numbers,  or  in  great  variety,  and  hence  it  may  frequently  be  neces- 
sary to  select  a  plain  tooth,  and  build  a  neck  of  gum-enamel  upon  it. 

This  may  be  done  in  a  most  artistic  manner  by  mixing  any  of  the 
gum-enamel  porcelain  "bo(hcs,"  of  the  proper  gum-color,  to  a  thick  con- 
sistency, and  building  an  extension  u])on  the  neck  of  the  facing  or  facings, 
of  proportions  which  will  adh  '  of  being  ground  to  the  desired  adaptation 
after  fusing. 

In  observing  this  jjrocedure  a  facing  of  the  exact  length  of  the  ad- 


375 

jacent  natural  crowns  (Fig.  268,  A),  or  one  even  longer  if  prepared  by 
grinding  a  shoulder  at  the  proper  point  (Fig.  268,  B),  should  be  selected, 
and  the  gum-enamel  then  built  on  and  fused,  after  which  it  may  be  ground 
to  the  desired  adaptation  (Fig.  268,  C),  and  one  fusing  is  usually  all  that 
is  necessary.  The  possibilities  in  this  connection  as  applied  to  the  anterior 
teeth  are  illustrated  in  Fig.  268,  D,  and  as  applied  to  the  bicuspids  have 
been  previously  illustrated  in  Fig.  257. 

Posterior  ''Dummies/' 

The  requirements  incident  to  the  application  and  construction  of 
dummies  for  the  posterior  part  of  the  mouth,  where  masticating  surfaces 
are  necessarily  involved,  present  phases  of  a  much  more  varied  and  com- 
plex character. 

This  is  due  largely  to  the  more  diversified  conditions  of  absorption 
and  occlusion  which  are  encountered  in  this  part  of  the  mouth,  and  which 
will  in  turn  govern  the  indications  for  the  application  of  any  of  the 
methods  used. 

The  requirements  of  contact  between  the  necks  of  artificial  teeth  and 
the  gum  tissue,  while  perhaps  not  so  exacting  as  compared  with  the  eight 
anterior  teeth,  for  purely  cosmetic  reasons,  are  nevertheless  an  important 
consideration,  and  may  be  summed  up  in  general  by  the  statement  that 
the  same  accuracy  of  adaptation  as  applied  to  the  anterior  teeth  should 
obtain,  or  else  there  should  be  no  contact  at  all,  and  this  applies  both  to 
the  facings,  or  to  the  body  of  the  bridge,  as  the  case  may  be  constructed. 

Porcelain  Taced  Bicuspids  and  molars. 

Perhaps  the  most  generally  applicable  and  commonly  used  st}  Ic  of 
construction  for  bicuspid  and  molar  "dummies"  consists  in  using  long- 
pin,  "flat-back"  porcelain  facings  in  combination  with  an  occlusal  sur- 
face of  gold. 

The  use  of  this  particular  method  is  indicated 

Jlpplication.  wherever    the    cosmetic    requirements    demand    the 

presence  of  porcelain,  and  yet,  where  the  demands 
for  strength  seem  to  contraindicate  the  employment  of  all-porcelain 
bridges — and  while  it  is  very  apparent  that  even  an  occlusal  surface  of 
gold  is  more  or  less  objectionable  on  any  of  the  twelve  anterior  teeth,  still 
the  fairly  esthetic  results,  combined  with  the  possibilities  for  strength,  and 
accuracy  of  occlusion,  make  such  a  type  of  construction  quite  generally 
useful. 


376 

In  selecting  the  facings  it  will  often  be  found 
Selection  of  that  those  designed  for  the  cuspid  teeth  can  be  used 

TacingS.  to  better  advantage  for  bicuspid  dummies,  than  can 

the  ''bicuspid"  facings  which  are  made  for  the  pur- 
pose. A  color  somewhat  darker  than  the  anterior  teeth  should  always  be 
obtained,  and  in  order  that  as  nearly  tmiform  proportions  as  possible  may 
prevail,  it  is  usually  better,  for  example,  to  fill  a  given  space  with  two 


/>-y. 


£€9. 


facings  of  fairly  good  size  than  with  three  small  ones ;  better  for  two 
reasons,  first,  because  the  size  will  usually  correspond  more  closely  with 
that  of  the  remaining  natural  teeth,  and  second,  because  less  grinding 
will  be  necessary,  and  hence,  greater  strength  will  result. 

When  the  facings  have  been  selected  and  ground 

Backing.  to  the  proper  adaptation  to  the  model,  and  with  an 

allowance    for   the  thickness   of  the   cusps,   zvithout 

destroying  the  occlusal  angles,  the  usual  preparation  of  the  occlusal  end 


for  the  backing  should  be  observed.  As  the  cusps  to  be  subsequently  at- 
tached will  afford  the  necessary  reinforcement,  a  single  backing  of  34 
gauge,  pure  gold,  is  all  that  is  required,  and  this  should  be  closely  adapted 
to  the  facing,  trimmed  to  the  cervical  shoulder,  as  indicated  in  anterior 
dummies,  and  even  with  the  approximal  edges.  A  slight  surplus,  however, 
should  remain  upon  the  occlusal  edge  (Fig.  269),  as  a  means  of  aiding 
in  the  adjustment  of  the  cusps,  and  of  insuring  the  penetration  of  the 
solder  between  them  and  the  backing,  thus  making  a  close,  flush  joint. 

While  the  cusps  may  be  formed  with  any  of  the 

Occlusion.  various  die-plate  systems,  the  best  results  are  usually 

to  be  obtained  by  making  special  cusps  to  fit  both 


Z77 

the  facing  and  the  occkision,  as  descrilied  in  connection  with  the  telescope 
crown,  and  for  the  same  reasons. 

When  the  cusps   are  to  be  constructed  in  this 

0arvcd  0U$P$.         manner,  the  backings  should  be  retained  to  the  fac- 
ings by  simply  bending  one  of  the  pins  down  upon  it, 
allowing  the  other  pin  to  remain  out  straight,  or  slightly  crooked.     The 
facings  should  now  be  adjusted  to  position  on  the  model,  and  temporarily- 
retained  thereon  from  the  buccal  side,  with  wax.     (Fig.  270.) 

Ordinary  means  of  preventing  the  plaster  from  adhering  to  the  model 
should  now  be  observed,  and  thin  well  mixed  plaster  then  poured  in 
against  the  backings,  and  the  articulator  firmly  closed.  After  hardening, 
the  plaster  cusps  thus  formed,  which  are  retained  to  the  facings  because 
of  the  position  of  the  remaining  pin,  should  then  be  trimmed  and  carved  as 
previously  described.     (Fig.  271.) 


In  the  carving,  any  interlocking  of  the  cusps  with  the  opposing  teeth 
should  be  avoided,  and  when  this  part  of  the  procedure  has  been  accom- 
plished in  a  satisfactory  manner,  tbe  plaster  cvisps,  with  their  respective 
facings,  may  be  separated  from  each  other  with  a  very  thhx  ribbon  separ- 
ating file,  or  mechanical  saw,  after  which  the  cusp-button,  or  die,  if  pref- 
erable, and  counter  die  for  each  one  should  be  made,  and  the  cusps  swaged. 

In  fitting  the  gold  cusps  to  the  facing,  when  the  plaster  cusps  have 
been  detached,  care  should  be  exercised  to  avoid  a  buccal  edge  of  gold 
which  would  be  necessarily  conspicuous,  hence  this  portion  of  the  cusps 
should  be  cut  away  until  when  approximated  with  the  backing,  only  a 
single  thickness  of  gold  remains  (Fig.  272),  and  this  should,  of  course, 
at  the  time  properly  occlude  w^ith  the  opposing  teeth. 

When  thus  fitted  and  all  overhanging  edges  or  anv  possible  impinge- 
ment is  avoided,  the  relation  should  be  sustained  with  wax,  and  each 
dummy  then  separately  invested  and  soldered. 

In    the    attacbment    of    facing    and    cusps    with 

Jlttacbing  Tadng       solder,    it    is    desirable    that    each    dummy    should 

and  0U$p$.  be    completed    as    nearly   as    possible ;    at   the    same 

time,  and  hence,  for  hygienic  reasons,  the  form  of  the 

lingual  surface  of  each  sliould  be  made  of  a  more  or  less  convex  shape,  in 


378 

order  to  avoid  the  formation  of  an  inaccessible  pocket  between  the  cusps 
and  the  gum,  when  the  bridge  is  finally  mounted.     (Fig.  273.) 

This  proper  form  may  be  obtained  by  carefully  shaping  and  fitting  a 
plate  of  22  k.  gold  about  30  guage  to  the  desired  outline,  after  investing, 
and  before  heating  the  case,  and  then  when  the  cusps  have  been  suffi- 
ciently reinforced  with  solder,  placing  this  form  in  position  and  simply 


attaching  it  to  the  edges  of  backing  and  cusps  with  solder.  (Fig.  274.) 
Such  a  type  of  construction  ofliers  the  advantages  of  economy  of  material, 
and  weight,  of  the  finished  piece,  and  is  particularly  applicable  to  large, 
long  facings. 

A  similar  shape  may  also  be  obtained  by  the  use  of  solder  alone ;  or 
scrap  gold  and  solder,  or  by  the  more  economical  means  of  partially  filling 
the  space  with  german-silver  forms  made  for  the  purpose  (Fig.  275),  or 
with  small  globules  of  pure  copper  or  silver,  any  of  which  may  be  used 
with  18K.  solder.     The  latter  procedures  are  permissible  providing  such 


Flq.  aiS. 


forms  or  globules  are  not  melted  in  the  fusion  of  the  solder,  thus  becoming 
alloyed  with  it,  and  also  provided  that  they  are  then  adequately  covered 
with  the  solder  so  as  to  completely  bury  them,  and  preclude  the  decidedly 
metallic  taste  which  would  be  very  apj^arent  and  objectionable  if  at  all 
superficially  exposed  to  the  action  of  the  secretions. 

The  early  practice  of  grinding  the  occlusal  ends  of  the  facings  flat 
and  blunt,  allowing  the  cusps  to  remain  of  uniform  depth,  filling  them 
flush  with  solder,  and  then  placing  the  facings  square  on  top  of  the  gold, 
without  any  intervening  backing,  is  not  productive  of  the  artistic  results 


379 

now  usually  demanded.  Facings  and  cusps  made  by  old  as  compared 
with  the  more  modern  method  when  the  angles  of  the  facing  are  preserved, 
are  shown  in  Fig.  276. 

The  making  of  cusp-forms  for  two  or  even 
Continuous  Cusps,  more  facings  at  one  time,  and  in  one  continuous 
piece,  is  sometimes  practiced,  but  is  not  as  reliable  a 
procedure  as  the  former  method  of  making  them  separately,  for  the 
reason  that  the  difficulty  of  accurately  fitting  such  forms  to  the  ends  of  the 
facings  and  to  the  occlusion,  at  the  same  time,  is  proportionately  increased, 
as  is  also  the  dansrer  of  fracturinsf  the  facinsfs  in  attaching  them  to  the 


Fi<j,  276 


Fiq.  £77. 


cusps.  Hence  the  former  type  of  construction  is  the  safest,  and.  in  general 
practice,  the  most  expedient  method.  Except  in  very  small  cases,  or  in 
rare  instances,  such  time-saving  procedures  should  not  be  resorted  to,  and 
are  not  productive  of  the  very  best  results. 

If   it  seems   desirable   or   expedient   to   employ 
Carved  Cusps,         such  methods,  however,  the  procedure  is  equally  ap- 
plicable to  carving  the  cusps,  or  using  die-plate  cusps, 
as  may  be  preferred. 


38o 

In  the  former  instance,  the  cusps  may  be  carved  as  usual,  and  the 
dies  made  at  one  time  without  separating  the  facings  and  cusps,  after 
which  the  cusps  may  be  swaged,  trimmed,  fitted  and  soldered,  thus 
completing  the  dummies  all  in  one  piece,  when  they  should  be  subsequently 
attached  to  the  abutment  pieces. 

When  it  may  seem  desirable  to  make  a  contin- 
DiC-plate  Cusps,        uous  chain  of  cusp-forms  by  the  die-plate  method  the 
Hollingsworth  system  perhaps  offers  the  most  favor- 
able opportunities. 

In  the  use  of  this  method  suitable  cusp-buttons  should  be  selected, 
placed  in  their  proper  relation  on  the  steel-plate  and  the  die  and  the 
counter-die  made,  after  which  the  gold  may  be  swaged  (Fig.  o."]"],  A),  the 
surplus  trimmed  away  (Fig.  277,  B),  and  the  adjustment  then  made,  as 
nearly  accurate  as  possible,  on  the  articulator  (Fig.  277,  C). 

The  requirements  of  occlusion,  together  with  the 

JIll-6old  Dummies,      limitations  of  space  may,  not  infrequently,  indicate 

the  employment  of  all-gold  dummies,  in  preference  to 

those  constructed  in  combination  with  porcelain  facings,  as  a  means  of 

insuring  the  greatest  possible  degree  of  strength  or  of  obtaining  absolute 

indestructibility  in  the  finished  piece. 

Even  though  the  increased  strength  obtainable 
Indications.  by  this  method  is  gained  at  the  expense  of  the  hieh- 

est  esthetic  requirements,  still  in  a  certain  limited 
class  of  cases  where  the  occlusion  upon  the  dummy,  or  dummies,  is  heavy ; 
where  the  space  is  either  abnormally  large  or  constricted ;  where  a  single 
dummy  is  to  be  placed  between  two  gold  crowns,  or  where  they  may  not 
be  within  the  range  of  vision,  or  too  flagrantly  conspicuous,  such  dummies 
may  be  used  to  good  advantage.  This  would  practically  confine  their 
application,  however,  to  the  substitution  of  second  molars  in  the  upper 
arch,  and  of  first  and  second  molars  in  the  lower  arch,  where  the  above- 
mentioned  requirements  and  conditions  seem  to  demand  an  absolutely  in- 
destructible dummy. 

When  tlic  abutment  ]ncces  have  been  completed 
Construction.  and  the  case  is  mounted  ui)on  the  articulator,  at  least 

two  general  methods  of  procedure  may  be  followed 
in  the  construction  of  this  style  of  dummy. 

First,  where  a  single  dummy  is  desired  the  entire  space  between  the 
crowns  may  be  varnished,  and  then  filled  with  soft  plaster,  and  the  articu- 
lator closed  into  proper  occlusal  relation,  after  which  this  plaster  may  be 
trimmed  and  carved  to  the  correct  occlusion,  and  to  the  desired  buccal 
outline  and  cervical  adaptation.     (Fig.  278,  A.) 


38i 

The  plaster  dummy  thus  formed  may  be  imbedded  in  mouldine  and 
a  die,  and  then  a  counter-die,  of  the  buccal  and  occlusal  surfaces  secured. 
(Fig.  278,  B.)  Twenty-eight  or  30  gauge  22K.  gold  should  now  be  care- 
fully swaged,  trimmed  and  fitted  to  position  on  the  models.    The  occlusal 


surface  of  the  cusps  may  then  be  reinforced  with  solder,  and  the  desired 
convexity  of  the  lingual  surface  obtained  by  soldering  a  backing  of  the 
same  gauge  gold,  to  the  edges,  or  by  filling  in,  as  previously  described  in 
connection  with  porcelain  face  dummies.  (Fig.  278,  C.)  The  typical 
application  of  such  dummies  to  practical  cases  is  shown  in  Fig.  278,  D. 


382 

Second,  the  time  thus  consumed  in  carving  a  plaster  dummy  may 
be  saved  by  using  an  ordinary  porcelain  tooth  designed  for  vulcanite 
work,  grinding  it  to  properly  fit  the  space  and  occlusion,  and  then  repro- 
ducing it  in  gold  of  the  above  gauge  and  karat,  by  means  of  an  imprint 
in  mouldine  and  fusible  metal  dies,  as  just  described. 

Either  method  is  productive  of  good  results,  and  where  two  or  even 
more  dummies  are  to  be  used  in  the  same  case,  this  procedure  should  be 
followed  for  each  dummy.  While  possible,  of  course,  it  is  scarcely 
practicable  to  make  them  continuous,  owing  to  the  combined  require- 
ments of  occlusion,  buccal  alignment,  cervical  adaptation  and  lingual 
contour,  for  all  of  these  can  be  better  observed  with  greater  facility  and 
accuracy  by  making  them  separately. 


^jcj.  21S. 


Dummies  involving  only  the  cusps,  or  occlusal 
Occlusal  surfaces,  may  also  be  found  to  be  a  particularly  use- 

Surfacc  Dummies.       ful  style  of  construction  in  cases  where  the  require- 
ments and  conditions  are  similar  to  those  just  men- 
tioned in  connection  with  "all-gold"  dummies,  but  where  contact  with 
the   ridge  is   unnecessary,  or   is   contraindicated    for   hygienic   or   other 
reasons. 

It  has  been  previously  emphasized  that  all  dum- 
TndicatiOltS.  mies  should  be  either  in  "absolute  contact  with  the 

ridge,"  or  that  "no  contact  at  all  should  exist,"  and 
hence  this  type  of  construction  is  particularly  useful  in  that  class  of 
cases  where  the  excessive  absorption  contraindicates  the  al^normal  exten- 
sion of  the  dummies  until  contact  is  afforded ;  where  the  restoration  of  the 
masticating  surface  is  all  that  is  required,  and  where  the  absence  of  por- 
celain facings  will  not  be  noticed. 

Thus  it  is  aj)parent  that  the  employment  of  this  style  of  construction 
is  applicable  chiefl)-  in  restoring  the  masticating  surfaces  of  molars, 
first,  where  considerable  absorption  has  taken  place,  and  particr.larly  in 


383 

the  lower  arch,  where  facing^s  are  unnecessary  for  cosmetic  reasons,  or 
where  their  absence  would  not  be  noticed ;  and  second,  where  the  neces- 
sarily more  or  less  unhygienic  condition  produced  by  contact  with  the  ridge 
would  be  entirely  overcome,  and  the  absolute  requirements  conserved  in 
the  most  hygienic  manner  possible. 

In  the  construction   of   such  dummies  -suitable 
Construction.  cusp-forms  may  be  made  by  any  of  the  methods  pre- 

viously advocated.  After  being  swaged  and  fitted  to 
the  occlusion  and  to  the  space  between  the  "attachments,"  they  should  first 
be  placed  on  an  asbestos  or  charcoal  block  and  filled  flush  and  even  with 
solder,  and  the  whole  then  invested  and  assembled. 


Fi(j.  £80. 

As  the  immediate  center  of  this  type  of  bridge  is  obviously  the  weak- 
est part  of  the  structure,  where  more  than  one  of  such  dummies  are  used 
in  a  single  piece  adequate  strength  must  be  obtained  in  the  final  assem- 
blage, and  this  can  usually  be  best  accomplished  by  fitting  a  piece  of  round 
iridio-platinum  wire  of  about  14  gauge  from  abutment  to  abutment,  and 
then  freely  covering  the  same  from  one  end  to  the  other  with  solder. 
Fig.  279  illustrates  the  typical  application  of  two  forms  of  such  con- 
struction. 


Cateral  6ravitation. 

Because  of  the  natural  tendency  of  teeth  to  move  toward  an  unoccu- 
pied area  in  the  arch,  it  not  infrequently  happens  that  one  immediately 
adjacent  to  a  space  caused  by  the  absence  of  a  single  tooth,  may  so  gravi- 
tate either  forward  or  backward  as  to  ultimately  occupy  a  positit^i  more 
or  less  in  the  center  of  the  space.     (Fig.  280.) 

In  such  conditions  of  lateral  gravitation,  or  similar  ones  due  to  non- 
eruption,  when  it  is  desirable  to  supply  the  missing  tooth,  one  of  two 
methods  of  procedure  is  usually  indicated.     Either  the  malposed  tooth 


384 

should  be  previously  brought  back  to  its  normal  position  in  the  arch,  or  its 
crown  mav  be  sacrificed  and  the  root  used  to  support  two  facings  of  suffi- 
cient proportions  to  fill  the  entire  space. 

If  the  age  of  the  patient  and  other  conditions 
Correction  seem  to  indicate  the  former  procedure,  and  to  contra- 

ct ntalpositlon.        indicate  the  destruction   of  the  natural  crown,  the 
method  of  attachment  to  the  malposed  tooth  shouki 


fi(f.  281, 


Ficj.  282. 


first  be  determined,  and  the  "attachment"  made  and  adapted  to  the  point 
of  finishing.  This  can  be  done  best  before  any  effort  to  move  the  tooth 
'  been  made,  for  the  reason  that  more  ample  space  exists,  and  that  the 
subsequent  soreness  during  the  fitting  is  thus  avoided. 

If  suitable  contact  of  the  "dummy"  with  the  natural  crown  of  the 
adjacent  toolli  is  jjrovidcd,  the  fixture  will  also  serve  the  ])urposc  of  hold- 
ing the  tooth  in  its  new  position,  and  ncj  other  form  of  retaining  apparatus 
will  be  required. 


'♦JfttacDment" 

and 

"Dummy"  Combined. 


3^5 

Wherever  the  age  of  the  patient,  or  the  sur- 
rounding physiological  conditions  may  seem  to  con- 
traindicate  regulation  of  the  malposed  tooth,  it  may 
be  deemed  practicable  to  sacrifice  the  natural  crown 
and  suspend  two  facings,  which  will  completely  fill 

the  space,  from  the  one  supporting  root.     (Fig  281.) 

When  this  procedure  seems  indicated,  any  provision  against  rotation, 

such  as  has  been  previously  recommended,  is  usually  unnecessary,  for  the 

reason  that  the  fulcrum  here  is  in  the  center,  and  hence  the  stress  to  which 

either  end  may  be  subjected  is  materially  diminished. 


F/q.  283. 


While  gold  may  be  used  in  combination  with  porcelain  facings  in 
such  instances,  the  most  artistic  results  are  to  be  obtained  from  a  platinum 
construction  and  porcelain  work,  because  the  cap  between  the  necks  of  the 
facings,  which  will  be  conspicuous  if  of  gold,  may  thus  be  hidden  by  the 
employment  of  gum  enamel  body  at  this  point. 

A  striking  evidence  of  the  possibilities  of  lateral  gravitation,  when 
augmented  by  poorly  adapted  bridges  and  an  unfavorable  occlusion,  is 
illustrated  in  Fig.  282.  It  will  be  observed  that  the  wearing  of  a  bridge 
supported  only  by  the  two  right  bicuspids  and  the  left  cuspid,  and  supply- 
ing the  missing  anterior  teeth  (previously  illustrated  in  Fig.  231,  A) 
without  proper  regard  for  the  occlusion,  has  resulted  in  forcing  these 
teeth  forward  until  they  are  the  full  space  of  one  tooth  anterior  to  their 
proper  position. 

In  the  reconstructed  case  it  will  be  noted,  however,  that  the  artificial 
substitutes  represent  the  proper  teeth  irrespective  of  the   fact  that  the 


386 

cuspid  on  the  left  side  supports  a  lateral  facing,  and  the  first  bicuspid 
on  the  right  side  supports  a  cuspid  facing.  (Fig.  283.)  This  fea- 
ture is  highly  essential,  and  should  always  be  observed  in  similar  condi- 
tions 

Opening  Of  tDc  ''Bstc." 

A  condition  quite  analogous  to  that  accruing  from  the  absence  of  ad- 
jacent teeth,  and  one  often  even  more  difficult  to  overcome  in  the  applica- 
tion of  fixed  bridges,  is  that  which  almost  invariably  results  from  the  ab- 
sence of  occluding  members  in  the  opposing  jaw. 


J=ic/.  284, 


Indeed,  whenever  the  teeth  of  either  jaw  are  de- 
ClongatiOlt,  privcd  of  their  normal  occluding  relations  for  any 

considerable  length  of  time  elongation  is  the  natural 
sequel,  and  such  conditions  are  often  encountered,  and,  in  proportion  as 
the  number  of  missing  teeth  increases,  arc  frequently  so  aggravated  as  to 
demand  the  opening  of  the  "bite"  to  an  extent  sufficient  to  admit  of 
accommodation  for  the  substitutes  which  are  required  to  fill  the  spaces 
and  restore  the  occlusion. 

Whenever  such  conditions  arc  encountered  good  models  should  first 
be  obtained  anrl  acciu-atcly  mounted  upon  the  articulator.  By  this  means 
it  may  then  be  definitely  determined  l)y  a  careful  study  just  how  much 
the  "bite"  sliould  l)e  o]x'ncd,  and  vvhirli  tootli,  or  Iceth,  may  best  be  used 
as  a  means  of  cstablisJiiiii^  tlic  desired,  or  nczv  relati<Mi  between  the-  jaws. 


387 


Fici.  285. 


Ficj.  286. 


When  this  tact  has  been  determined  separate  crowns  constructed 
so  as  to  meet  such  requirements  should  be  made,  and  temporarily  mounted 
with  gutta-percha.  After  the  occlusion  is  thus  established  by  one  or  more 
crowns,  the  construction  of  the  remaining  work,  which  will  supply  the 
missing  teeth  and  permanently  sustain  the  occlusion  thus  fixed,  should  fol- 


388 


Ficf.  887. 


Ficf.  aaa. 


low ;  but  in  such  conditions  all  of  the  posterior  teeth  on  each  side  must 
occlude  when  the  operation  is  completed,  for  otherwise  the  work  of  masti- 
cation would  be  thrown  upon  only  a  few  teeth,  and  this  would  result  in 
subsequent  trouble.  For  this  reason  the  new  relation  must  not  be  per- 
manently established  by  the  final  mounting  of  the  work  until  all  teeth 
involved  are  completed. 


389 


Fi<j.  889. 


fitf.  RBO. 


A  typical  case  is  illustrated  in  Fig.  284,  where  practically  no  occlu- 
sion has  existed  for  a  great  many  years,  but  where  by  cutting  down  the 
elongated  teeth,  and  opening  the  "bite"  by  tlie  construction  of  the  lower 
bridge  on  the  right  side,  first,  a  more  or  less  perfect  occlusion  of  all  the 
posterior  teeth  was  made  possible. 


390 


Fiq.  29 L 


Fiq.  £98. 

Similar  conditions  often  present  as  a  result  of 
Jibrasion.  the  loss  of  some  of  the  occluding  teeth,  complicated 

with  that  distressful  waste,  or  "melting  away,"  of 
tooth  structure  known  as  abrasion.  In  these  cases  an  opening  of  the 
"bite"  is  frequently  indicated  as  a  means  of  arresting  the  progress  of  this 
combined  mechanical  and  chemical  influence,  and  of  preserving  the  nat- 
ural crowns  of  the  remaining  teeth,  by  throwing  the  actual  work  of  masti- 
cation upon  the  artificial  teeth  exclusively.  In  this  class  of  cases,  how- 
ever, the  opening  of  the  bite  must  be  accomplished  in  such  manner  as  to 
involve  as  much  as  possible  all  of  the  masticating  teeth  and  thus  avoid 
throwing  the  work  on  only  a  few. 


391 
CVPtcal  JlpplicatiotL 

Whilst  it  would  be  quite  impossible,  and  is  indeed  equally  unneces- 
sary, to  attempt  to  illustrate  all  variations  of  bridge  construction  for 
"fixed"  appliances  where  /"////  crozciis  are  used  as  the  attachments,  which 
would  be  more  or  less  practical ;  and  while  the  fundamental  underlying 
"principles"  have  already  been  discussed  in  their  proper  place,  still  for 
the  benefit  of  the  inexperienced  operator  it  is  deemed  expedient  to  illus- 
trate some  of  the  more  typical  applications  which  are  embraced  in  the 
preceding  types  of  construction. 


F/cj.  293. 


Ficj.  S9il. 


For  this  reason  the  accompanying  illustrations  arc  presented  with  a 
view  to  covering  a  range  extending  from  the  most  sim])le  to  the  most 
extensive  structures,  and  it  will  be  observed  that  the  application  of  each 
respective  type  is  practicable  in  accordance  with  the  requirements,  as  pre- 
viotislv  indicated,  except,  of  course,  that  in  the  more  extensive  cases,  such 
as  is  illustrated  in  Fig.  292.  the  use  of  the  cuspid  instead  of  the  central 
incisor  roots  would  be  a  far  more  practicable  procedure. 


Dii^mifica  Principles. 


CHAPTER  XXII. 

Interrupted    Bridges:    Indications,   Application.      Saddle   Bridges:    Indications;    Ex- 
cessive   A-bsorption,    Extension    Bridges,   Unfavorable   Occlusion,    Porcelain 
Bridgework,   From   a   Hygienic   Viewpoint,    Contraindications,    Re- 
quirements,  Application.      Extension   Bridges :    Indications. 


The  preceding  methods  of  construction  while  designated  as  the 
typical  and  orthodox  procedures,  do  not  entirely  constitute  the  sum  total 
of  those  which  occupy  a  permanent  sphere  of  usefulness  in  the  construc- 
tion of  fixed  bridgework. 

While  it  would  be  useless  to  attempt  specifically  to  describe  the 
myriad  of  methods  which  have  been  devised  from  time  to  time,  and 
while  many  of  them — still  re^commended  in  text-books — have  already 
proven  to  be  impracticable,  and  some  have  even  become  obsolete,  yet 
others  possess  such  merit  as  to  warrant  the  classihcation  and  considera- 
tion which  follows. 

Inferruptcd  Bridges. 

Among  the  most  prominent  types  belonging  to  the  classification  of 
"diversified  principles"  is  the  one  wherein  the  presence,  at  some  point 
in  the  arch,  of  a  natural  tooth  which  is  not  needed  nor  used  as  an  abut- 
ment, may  cause  an  interruption  in  the  otherwise  continuous  relation  of 
the  various  parts  comprising  the  piece,  and  the  particular  type  of  con- 
struction thus  resulting  is  designated  an  "interrupted"  bridge. 

Whilst  as  a  general  rule  it  is  always  better  and 

Indications.  safer  to  employ  a  maximum    nstead  of  a  minimum 

number   of   abutments,   still    there  is   nevertheless  a 

limited    class    where    the    utilization    of   certain    remaining   good    sound 

teeth   is  unwise  or  unnecessary,  and  therefore   contraindicated,  because 

of   the   opportunity    for   otherwise    obtaining   adequate    strength    in    the 


393 

attachment  of  the  piece.  It  is  true  that  such  cases  are  the  exception 
rather  than  the  rule  ;  yet  when  they  do  present  it  would  be  manifestly 
unwise  to  involve  a  good  tooth  which  is  not  actually  needed  in  the  sup- 
port of  the  bridge.  Such  breaks  in  the  continuity  of  the  structure, 
however,  should  rarely  if  ever  exceed  the  space  of  a  single  tooth,  and 
this  should  be  principally  in  the  upper  denture,  and  anterior  to  the  first 
molar. 

In  the  application  of  such  a  type  of  construc- 
HPflicatiOlt.  tion  it  is  vitally  necessary  to  observe  that  the  con- 

nection between  the  parts  on  each  side  of  the  remain- 
ing tooth  be  made  in  such  manner  as  to  insure,  first :  adequate  strength 
in  the  completed  structure,  and  second  :  a  relation  between  the  connecting 
bar,  the  tooth,  and  the  gum  which  will  afford  opportunity  for  cleanliness 


FJci.  295. 


admit  of  the  normal  occlusion,  and  offer  as  little  obstruction  to  the  move- 
ments of  the  tongue  as  possible.  To  obtain  the  latter  features  the  bar 
should  rest  lightly  upon  the  gum  but  should  not  come  in  contact  with 
the  natural  tooth. 

This  connecting  bar  should  be  made  of  round  iridio-platinum  wire, 
14  to  16  g,  and  should  be  cut  the  proper  length,  the  ends  then  flattened 
on  the  anvil,  and  the  desired  adjustment  made  to  the  model  just  prior 
to  investing  the  case.  (Fig.  295.)  The  application  of  the  principle  to 
two  typical  cases  is  illustrated  in  Fig.  296. 

Saddle  Bridges. 

As  previously  indicated  under  the  caption  of  "classification"  the 
term  "saddle  bridges"  is  applied  to  that  type  wherein  the  body  of  the 
bridge  which  supports  the  "dummies"  intervening  between,  or  adjacent 
to,  the  abutments,  is  conformed  to  the  outline  of,  and  placed  in  direct 
contact  with  the  contiguous  soft  tissue. 


394 

The  practicability  of  this  method  has  long  been,  and  indeed  perhaps 
still  is  a  somewhat  mooted  question,  but  it  may  nevertheless  be  safely 
asserted  that  whilst  the  possible  virtues  of  the  principle  involved  will 
increase  or  diminish  in  proportion  to  the  degree  of  accuracy  obtained  in 
the  adaptation,  the  ntilify  ■ivhcn  judiciously  employed,  is  unquestionable. 


Fi'cj.  296 


Preliminary  to  the  general   indications   for  the 

Indications,  selection   of  this   type   let  it  be   said    witli   emphasis 

that  they  are  first  governed   entirely  by  the  ability 

of  the  operator  to  recognize  and  appreciate  the  requirements  of  judicious 

application,  and  then  to  skilfully  execute  those  of  accurate  adaptation. 


395 

In    cases    of    excessive    absorption   where    gum 
€xccs$i»e  restoration  is  demanded,  as  illustrated  in  two  classes, 

Jibsorption.  for  example,  in  Fig.  297,  a  "saddle"  is  as  essential 

as  is  the  proper  selection  and  arrangement  of  the 
artificial  substitutes  themselves,  for  the  reason  that,  in  fixed  bridgework, 
only  by  such  means  may  the  required  restoration  and  its  proper  adapta- 
tion be  effected. 

The  use  of  the  saddle  is  also  indicated  in  ex- 

6xten$ion  tension  bridges   where  one   or  more  posterior  teeth 

Bridges.  supplying  masticating  surfaces,  or  which  are  to  be 

subjected  to  masticating  stress,  are  carried  anterior 

or  posterior  to  the  abutment  or  abutments.     In  such  cases  the  abutments 

must,  of  course,  necessarily  possess  sufficient  strength  per  sc  to  afford 

ample  and  permanent  support  to  the  dummies,  and  the  occlusion  should  be 

such  as  to  throw  a  preponderance  of  the  stress  imposed  upon  the  roots  sup- 


Fiej.  297. 


porting  the  work,  but  a  proper  rest  upon  the  tissue  will  then  enable  the 
dummies  to  offer  and  sustain  a  degree  of  resistance  sufficient  to  make 
them  comfortable  and  serviceable.  If  such  a  condition  is  not  obtained, 
and  the  work  assumed  by  the  dummies  is  thrown  entirely  upon  the  abut- 
ments, it  is  but  natural  to  expect  the  destruction  or  displacement  of  the 
piece,  or  the  ultimate  loosening  and  loss  of  the  roots. 

In  those  cases  where  the  position  of  the  oppos- 

Unfavorable  ing  natural  teeth,  or  the  absence  of  some  of  them, 

Occlusion.  necessarily  throws  the  greater  portion  of  the  stress 

of  mastication  upon  the  dummies,  and  perhaps  even 

precludes  any  occlusion  of  the  abutments,  a  rest  upon  the  tissue  beneath 

the  area  of  greatest  stress  is  indicated.     The  relief  thus  afforded  to  the 

abutment  roots,  especially  where  the  span  is  a  long  one,  and  the  additional 

strength  afforded  to  the  piece  at  its  weakest  point  will  often  admit  of  the 

practical   and  permanent  application   of  a   "fixed"   bridge   which  would 

otherwise  prove  a  failure.      (Fig.  298.) 


396 

Also  in  conditions  known  as  "close  bite,"  the  utilization  of  the 
saddle  may  be  indicated  as  a  means  of  obtaining  strength  in  the  com- 
pleted structure. 

The     saddle     is     particularly     indispensable     in 

Porcelain  porcelain    work,    for    the    reason    that    the    friable 

BridSCWOrh,  nature  of  this  material  demands  that  such  portions 

of  it  as  form  masticating  surfaces  and  which  are  to 

be    subjected    to   masticating    stress    must   be   protected   and    supported. 

Since  the  strength  of  this  material  increases  in  proportion  to  its  bulk, 

as  much  as  is  consistent  must  be  used  in  reproducing  contour,  and  the 

saddle  affords  the  only  adequate  means  of  supporting  the  superstructure ; 


Fiq.  298. 

hence,  from  this  viewpoint,  it  makes  possible  the  more  permanent  success 
of  this  class  of  work. 

Contrary   to  the  generally  accepted   belief  that 
the  Saddle  ^  saddle  is  decidedly  imhygienic,  such  a  device  is  fre- 

from  a  l^ygicnlc       quently  indicated  in  order  to  obtain  a  closer  approach 
Uiewpoint,  to  hygienic  results. 

For  instance,  in  cases  where  the  occlusal  sur- 
faces of  the  opposing  teeth  in  occlusion  are  in  close  proximity  to  the 
tissue  in  the  space  to  be  bridged,  a  condition  commonly'  called  a  "close 
bite,"  and  where  the  dummies  to  be  supplied  must  possess  a  masticating 
surface  in  order  that  such  a  bridge  may  be  serviceable  as  well  as  orna- 
mental, the  use  of  a  well  adapted  saddle  will  result  in  a  far  more 
hygienic  condition  than  the  lingual  shelf  fornicd  by  the  attachment  of 
cusps  to  the  facings. 

While  in  such  cases  the  cusps  should  not  be  large  bucco-lingually, 
and  the  lingual  surface  of  each  dummy  should  be  properly  contoured,  if 
possible,  the   surface  of  a  bridge  brought   into   close   contact  with   the 


397 

tissue  will  often  prove  far  more  hygienic  than  the  absolutely  inac- 
cessible recesses  resulting  from  the  usual  method  of  construction.  In 
this  connection  the  surface  of  a  well  adapted  saddle,  and  the  possi- 
bilities for  gum  reproduction  and  lingual  contour  afforded  by  it,  will 
often  render  the  work  cleaner  and  more  comfortable  to  the  patient  than 
the  ordinary  construction,  which  with  even  favorable  opportunity  is 
often  neglected,  even  by  well-advised  and  scrupulously  cleanly  patients. 

The  question  very  naturally  arises  as  to  just  what  condition  the 
tissue  under  such  circumstances  may  ultimately  present,  and  what,  if 
any,  physiological  change  or  pathological  disturbance  will  occur. 

Upon  the  removal  of  such  bridges  worn  from  three  to  five  years, 
where  the  adaptation  had  been  good,  the  surfaces  of  the  saddles  have 
been  found  clean  and  comparatively  free  from  accumulations,  except 
some  little  exfoliated  epithelium ;  the  patients  had  experienced  no  particu- 
larly unpleasant  taste  nor  offensive  odors,  and  the  tissues,  while  pre- 
senting a  slightly  reddened,  somewhat  congested  appearance,  due  perhaps 
to  a  superficial  capillary  stasis,  as  a  result  of  the  pressure,  indicated  no 
marked  evidences  of  soreness,  inflammation,  hypertrophy  nor  resorption. 
Such  results  could  only  be  expected,  however,  where  a  good,  close 
adaptation  without  irritating  influences  existed. 

Whatever  merit  and  advantages  a  saddle  may  possess,  and  however 
useful  it  may  sometimes  prove,  however,  there  are  conditions  contra- 
indicating  its  use  quite  equal  in  importance  to  those  demanding  it,  and 
these  must  be  observed  even  more  closely  in  order  to  preclude  the  evil 
results  of  an  unnecessary,  unwise,  or  injudicious  application. 

In  bridges  extending  anteriorly  to  the  second 
Contraindications,  bicuspid  where  no  masticating  surface  is  necessary, 
as  has  been  said,  it  is  often  practical  to  carry  one 
"dummy"  without  any  support  upon  the  tissues  beneath  it,  but  in  such 
cases  the  abutment  from  which  it  is  extended  should,  of  course,  possess 
sufficient  strength,  and  should  assume  a  preponderance  of  the  stress 
imposed. 

The  saddle  is  also  unnecessary,  and  consequently  contraindicated,  in 
those  cases  where  the  abutment  roots  are  close  enough  together  and 
sufficiently  strong  to  withstand  the  stress  assumed  by  the  entire  fixed 
structure ;  where  the  occlusion  is  favorable,  and  where  every  opportunity 
is  afforded  for  the  self-cleansing  contour  of  the  lingual  surface. 

The  saddle  is  also  contraindicated  in  all  cases  where  thorough  and 
complete  absorption  of  the  tissues  has  not  taken  place.  If  this  is  not 
observed  the  subsequent  absorption  will  not  only  destroy  the  usefulness 
of  the  saddle,  but  will  result  in  a  decidedly  unhygienic  condition. 


398 

As  the  success  of  the  saddle  is  so  dependent  upon  a  proper  and 
sufficiently  close  adaptation,  it  is  also,  of  course,  always  contraindicated 
whenever  and  wherever  every  facility  is  not  offered  for  such  relation. 

A     consideration     of     the     requirements     must 

K^quirementS.  begin   by    repeating    and   specially    emphasizing   the 

assertion  that  the  success  and  usefulness  of  a  saddle 
wall  increase  in  proportion  to  the  accuracy  of  its  adaptation.  It  must  fit 
the  tissue  perfectly  and  must  rest  upon  it  with  uniform  pressure  at  all 
points  so  as  to  afford  some  little  relief  to  the  abutments,  and  to  preclude 
the  infiltration  of  food-laden  secretions  betw^een  it  and  the  tissue  upon 
which  it  rests ;  yet,  of  course,  not  sufificiently  hard  to  cause  capillary 
stasis,  or  to  induce  reabsorption.  In  size  it  should  be  no  larger,  nor  cover 
a  greater  area  than  is  absolutely  essential  to  the  work  to  be  assumed  by 
the  teeth  it  is  intended  to  support,  and  the  edges  should  be  rounded  and 
smooth,  so  as  to  exert  no  possible  irritating  influence.  It  should  also  be 
made  of  a  metal  w^hich  is  least  susceptible  to  the  chemical  action  of  the 
secretions.  For  this  reason  the  use  of  platinum  is  universally  indicated, 
because,  this  metal  is  least  affected  when  subjected  indefinitely  to  such 
action,  and,  in  consequence,  will  more  permanently  retain  its  color  and 
lustre,  and  remain  cleaner,  than  gold  of  any  degree  of  fineness. 

The     importance     of    adaptation     has     already 
Jlpplication.  been    mentioned,    and    while   various    methods    have 

been  employed  as  a  means  of  obtaining  this,  it 
is  often  accomplished  with  difficulty.  The  following  method,  how- 
ever, will  overcome  many  obstacles  and  insure  a  degree  of  accuracy 
which  will  add  much  to  the  practicability,  serviceability  and  cleanli- 
ness of  the  saddle.  The  "attachments"  or  "abutment  pieces"  should 
first  be  completed  as  usual  and  adjusted  to  position  on  the  roots. 
An  impression  of  them  and  the  intermediate  or  adjacent  tissue  should 
then  be  taken  with  plaster.  If  the  crowns  are  withdrawn  in  the 
impression  they  should  be  removed  thereform  and  laid  aside  for  the 
time.  The  open  ends  of  the  impression  should  then  be  filled  in  with 
moldine  or  plaster,  and,  if  necessary,  the  whole  may  be  built  up  or 
extended  sufficiently  to  give  adequate  body  and  strength  to  the  metal 
model,  or  die.  After  drying,  the  die  should  be  secured  with  any  fusible 
alloy,  and  this  will,  of  course,  present  a  perfect  reproduction  of  the  abut- 
ment pieces  in  position,  and  their  relation  to  the  tissue  upon  which  the 
saddle  is  to  rest.  This  die  should  then  be  built  up,  as  above  suggested, 
in  order  to  form  a  matrix  for  the  counter-die,  in  which  it  is  only 
necessary  to  leave  the  surface  of  the  crowns,  or  attachments,  presenting 
toward  each  other,  and  the  ridge,  exposed.     After  coating  the  exposed 


399 

surfaces  with  a  thin  solution  of  whiting,  which  will  be  found  to  be  the  best 
and  cleanest  separating  medium,  the  counter-die  may  then  be  easily 
obtained  with  the  same  alloy.  Die  and  counter-die  are  shown  in  Fig.  299. 
Thirty-two  gauge  platinum,  or,  iridio-platinum  if  stiffness  is  desired, 
should  then  be  swaged  and  trimmed  to  the  required  form.  Twenty-two 
karat  gold  of  the  same  thickness  may  be  used  in  an  emergency,  but  the 
former  is  preferable. 


The  shape  and  conformation  of  the  tissue  upon  which  the  saddle 
is  to  rest,  and  the  size  of  the  dummies  to  be  supported,  should  guide 
in  the  shape  and  form  given  to  it.  In  broad,  flat  ridges  the  saddle  may 
be  proportionately  larger,  of  course,  than  in  thin,  sharp,  narrow  ones, 
the  usual  width  varying  from  three  to  five-sixteenths  of  an  inch,  except 
that  in  the  latter  class,  in  the  lower  jaw,  the  convex  surface  of  a 
half-round  wire  of  suitable  size,  placed  in  contact  with  the  ridge,  will 
often  answer  nicelv.     When  the  wider  saddle  seems  indicated,  however, 


Fiq. 


300. 


and  particularly  in  the  upper  jaw,  it  is  usually  best  to  leave  it  full  width 
immediately  beneath  the  dummies  only,  by  cutting  it  away  to  some  extent 
in  the  interproximal  spaces  as  originally  suggested  by  Dr.  W.  H.  Taggart. 
(Fig.  300.)  Such  a  shape  affords  opportunities  for  sufficient  support 
and  lingual  contour  beneath  the  dummies,  and  especially  in  gold  work, 
less  conspicuous  and  cleaner  interproximal  spaces. 

\Mien  properly  swaged  and  trimmed  the  "attachments"  or  abutment 
pieces  should  be  adjusted  to  position  and  the  saddle  finally  adapted  and 


400 

trimmed  to  the  desired  outline,  in  the  motith.  Each  end  should  be  fitted 
so  as  to  come  in  direct  contact  with  the  crowns  or  "attachments"  when 
slight  pressure  is  applied,  and  the  edges  should  not  be  allowed  to  lap 
over  upon  them,  as  such  a  joint  might  destroy  the  accuracy  of  adapta- 
tion at  this  more  or  less  vulnerable  point. 

It  now  becomes  necessary  to  preserve  an  absolutely  accurate  relation 
between  tissue,  saddle  and  abutment  pieces  until  the  same  is  permanently 


iiiillP'" 


sustained  by  soldering.  This  can  be  accomplished  by  taking  an  impression 
of  the  parts  in  position,  in  plaster,  with  sufficient  pressure  upon  the 
saddle  to  insure  a  slight  bearing  upon  the  tissue.  This  may  be  secured 
by  the  use  of  a  prop  of  orangewood,  of  suitable  length  to  keep  the 
mouth  open,  with  one  end  resting  upon  the  center  of  the  saddle  and  the 
other  against  the  opposing  teeth  or  ridge.  (Fig.  301.)  With  this  so  ad- 
justed, and  a  firm  closure  upon  it,  the  saddle  is  gradually  and  gently 
forced  against  or  into  the  tissue,  when  the  impression  can  be  taken 
without  relieving  the  pressure.  For  this  purpose  may  be  used  an  ordinary 
impression  tray  with  a  slot  cut  into  it  from  the  heel  sufficiently  wide  to 
accommodate  or  straddle  the  jjrop,  so  that  when  filled  with  plaster  it  may 


401 

be  easily  carried  to  place.     (Fig.  302.)     By  such  means  a  uniform  press 
ure  such  as  may  scarcely  be  obtained  in  any  other  manner  is  sustained, 
and  the  closeness  of  the  relation  is  proven  by  the  fact  that  the  plaster 
seldom  penetrates  beneath  the  saddle   in  taking  the  impression. 

If  this  method  is  not  adopted  similar  results  may  be  obtained  by 
tightly  fitting  a  wedge  of  wood  between  the  abutment  pieces,  and  then 
closely  packing  a  rather  stiff  wax,  or  temporary  stopping,  between  the 


wedge  and  the  saddle  in  such  manner  as  to  hold  the  latter  firmly  in  place 
against  the  tissue.  Care  must  be  exercised,  however,  to  leave  at  least 
the  edges  of  the  saddle  so  exposed  as  to  obtain  an  imprint  in  the  impression 
which  will  insure  its  proper  replacement  and  retention  therein  after 
removing  and  before  filling.     (Fig.  303.) 

A\'hcn  the  impression  has  been  secured  it  should  be  varnished  and 
then  filled  with  iiivcstiiioit  material,  which,  after  separating,  will  admit 
of  the  permanent  attachment  of  the  parts  with  solder.  The  piece  should 
then  be  replaced  in  the  mouth  and  the   edges  of  the   saddle  carefully 


402 

burnished  to  a  close  and  accurate  adaptation  with  a  suitable  and  fairly 
heavy  burnisher,  when  the  "bite"  and  final  impression  for  the  completion 
of  the  work  should  be  secured. 

These  orangewood  props,  or  wedges,  should  be  cut  in  various  lengths 
to  meet  the  requirements,  and  may  be  made  applicable,  where  there  are 
no  opposing  teeth,  by  covering  the  end  which  rests  upon  the  tissue  in 
such  cases  with  a  cushion  of  modelling  compound  or  sealing  wax. 
(Fig.  304.) 


Eici.  303. 


Ficj^BQA, 


In  the  mounting  of  fixed  bridges  where  a  saddle  is  used,  several  pre- 
cautions must  be  observed.  Those,  together  with  other  closely  allied 
considerations,  will  be  subsequently  presented  and  fully  discussed  under 
the  subject  heading  of  "mounting." 

Extension  Bridges. 


The  type  known  as  "Extension"  bridges  embodies  the  extension  of 
one  or  more  "dummies"  anterior  or  posterior  to  the  abutments,  either 
with  or  without  a  "saddle"  resting  upon  the  contiguous  soft  tissue,  and 
except  in  those  cases  previously  mentioned  where  a  single  tooth  is 
suspended  from  a  single  abutment,  is  without  doubt  one  of  the  most 
pernicious  practices  incident  to  the  application  of  "fixed"  structures. 

Whilst  the  principle  involved  in  nearly  all  types  of  construction 
other  than  those  mentioned  is  mechanically  wrong  and  much  injury  to, 
and  even  the  possible  loss  of  the  supporting  teeth,  may  result,  yet  there 
are  occasional  instances  where  the  application  may  be  made  more  or 
less  practicable. 


403 

Such  instances  are  necessaril}-  confined  to  those 

TndiC(ltion$.  cases    where   the   conditions   may   be,   or   are,    made 

favorable  by   the   ratio  between  the  stress  received 

by  the  "dummies"  so  extended,  and  the  inherent  strength  and  stabihty  of 

the  abutments. 

For  instance,  as  has  been  previously  stated,  certain  teeth  in  the  arch 
are  quite  capable  of  supporting  a  single  extended  "dummy"  under  the 


^^^^.T^-^Tiiir^ 


Fici-  305. 

conditions  mentioned  in  connection  therewith  (see  "principles"^ ,  but  no 
one  tooth  will  support  more  than  a  single  dummy  in  any  conceivable 
manner,  for  any  length  of  time. 


Fiq.  306. 


The  practice,  therefore,  of  suspending  even  a  small  "dummy"  on  each 
side  of  a  single  abutment,  which  unfortunately  is  sometimes  observed, 
(Fig.  305),  is  so  remote  from  sound  mechanical  principles  and  even  from 
reason  and  common  sense,  as  to  be  vicious,  and  the  see-saw,  teter-board 
movement  thus  invited  will  invariably  result  in  the  very  early  loss  of  the 
supporting  tooth. 


404 

Another  practice  not  uncommon  is  the  extension  of  single  anterior 
dummies  from  posterior  abutments  with  remaining  natural  teeth  inter- 
vening, as  shown  in  Fig.  306, 

While  some  means  of  supporting  substitutes  for  missing  anterioi 
teeth  without  involving  the  mutilation  of  adjacent  good  sound  teeth  would 
be  eminently  desirable,  it  must  nevertheless  be  remembered  that  in  pro- 
portion as  the  point  which  receives  the  stress  is  removed  from  the 
fulcrum,  or  point  of  resistance,  the  stress  becomes  increased,  and  the 
resistance  correspondingly  diminished,  and  that  under  such  influence, 
therefore,  the  displacement  or  loss  of  the  supporting  tooth  becomes  only 
a  question  of  time. 


/=>y.  307. 


Bq.  3(m, 


Granting  that  the  abutment  thus  employed  may  be  so  supported 
by  the  roots  of  the  adjacent  teeth  as  to  fortify  it  to  a  greater  or  less 
extent  against  displacement,  and  granting  also  that  the  extension  bar 
may  first  be  swaged  of  pure  gold,  and  thus  well  and  closely  adapted  to 
the  tissue  upon  which  it  rests,  and  may  then  be  stiffened  and  strengthened 
by  clasp  metal  and  solder,  all  of  which  is  necessary,  it  nevertheless  rests 
upon  soft  tissue,  which,  together  with  the  elasticity  of  the  metal  would 
necessarily  admit  of  some  movement  under  stress^,  and  as  a  result  the 
extension  bar  would  soOn  become  imbedded  in  the  soft  tissue ;  the  sus- 
pended "dummy"  become  too  short;  and  the  tissue  beneath  botli  so 
hyperacmic  and  inflamed,  that  the  supporting  tooth  would  prove  unequal 
to  the  demands,  and  the  fixture  would  become  a  failure. 

It  is  therefore  evident  that  such  a  type  of  construction  should  only 
be  used  in  rare  instances,  as  a  last  resort,  or,  for  temporary  purposes,  if 
indeed  at  all. 

Perhaps  tlic  most  favorable  situation  for  this  i)articular  type  of 
construction,   aside   frrjm   tliose   already   niLiilioncd   as   ap])lic(l   to   single 


405 

adjacent  teeth,  would  be  in  such  cases  as  illustrated  in  Fig.  307,  where 
two  or  possible  three  posterior  teeth  upon  one  or  both  sides  may  be 
extended  from  several  anterior  abutments. 

In  such  cases  if  a  supporting  "saddle"  were  adapted  in  accordance 
with  the  requirements,  and  the  occlusion  then  made  hardest  upon  the 
anterior  teeth ;  or,  if  the  opposing  teeth  were  artificial,  or  some  of  them 
absent,  some  hope  may  be  indulged  for  the  serviceability  and  permanency 
of  the  fixture,  but  this  will  then  be  in  proportion  as  the  stability  of  the 
supporting  teeth,  and  the  condition  of  the  contiguous  tissues  may  be 
favorable. 


Also,  another  class  of  cases  where  such  principles  may  be  applied 
with  some  hope  of  reasonable  utility  and  permanency  is  sometimes 
found  where  all  of  the  molar  teeth  are  missing  in  the  lower  arch,  and 
where  for  cosmetic  reasons  as  well  as  from  a  viewpoint  of  possible 
utility  it  may  be  desirable  to  supply  one  molar  on  each  side. 


4o6 

In  such  instances  if  the  occhision  and  other  environments  are,  or 
may  be  made,  favorable,  the  tzvo  bicuspids  may  be  used  to  support  one 
suspended  molar  tooth,  but  in  no  instance  more  than  one,  and  this  should 
be  supported  by  a  well  adapted  saddle,  and  the  occlusion  so  adjusted  as 
to  be  harder  upon  the  abutments  than  upon  the  dummy.  Such  cases  have 
been  known  to  serve  successfully  for  a  number  of  years.     (Fig.  308.) 

Another  type  of  construction  in  which  the  first  bicuspid  is  used  to 
support  a  missing  lateral,  thus  combining  both  the  "interrupted"  and 
"extension"  principles — which  is  practicable  under  favorable  conditions — 
is  shown  in  Fig.  309A,  and  still  another  class  of  cases  where  the  number, 
stability  and  position  of  the  abutments  may  admit  of  extending  even  two 
dummies  anterior  to  them  with  reasonable  assurances  of  success  and 
permanency,  is  illustrated  in  Fig.  309B. 

In  such  instances  it  will  be  observed  that  but  little  actual  work  is 
required  of  the  "dummies"  thus  extended,  as  compared  with  that  assumed 
by  the  rest  of  the  structure,  and  this  accounts  for  the  possible  practicability 
of  such  application.  Whenever  it  can  be  done  it  is  usually  best  in  the 
latter  instance,  however,  to  add  to  the  support  of  the  extended  "dummies" 
by  means  of  a  well  adqjted  saddle. 


Detachable  ana  Replaceable  teetb 


CHAPTER  XXIII. 

Davis  Crowns.     Brewster  Bridge  Teeth.     The  Boos  ]\Iethod.     Roach's  \YedgeIock 

Bridge  Teeth.     Steele's  Crown  and  Bridge  Tooth.    The  Louque  Method. 

Bryan's   Methods.      Townsend's   ^Method. 


Among  the  diversified  methods  which  are  now  in  use,  and  which 
are  regarded  as  being  practicable  when  their  appHcation  is  indicated,  are 
those  wherein  the  various  forms  of  defcicJiablc  and  replaceable  teeth  or 
facings  are  used. 

The  principles   involved    in   this   class   of   work 

Jldl?antagc$.  possess  at  least  three  important  advantages.     First, 

the  cosmetic  possibilities  of  the  finished  structure  are 
enhanced  by  avoiding  the  display  of  gold  incisal  edges  and  occlusal 
surfaces.  Second,  the  absence  of  any  need  for  subjecting  the  porcelain 
teeth  to  the  heat  of  soldering;  and,  third,  the  increased  facility  for 
effecting  repair  in  the  event  of  subsequent  accident. 

The  first  advantage  is  readily  apparent  because  any  method  by  which 
the  conspicuous  display  of  gold  may  be  avoided  has  always  been  welcomed 
by  the  aesthetic  and  progressive  prosthodontist,  to  whom  the  usual  form 
of  dummy  made  by  the  joining  of  porcelain  facing  and  gold  cusps  has 
always  been  objectionable.  Such  operators  have  for  years  been  await- 
ing the  introduction  of  some  form  of  porcelain  tooth,  more  like  the 
old  "tube"  tooth,  particularly  for  bicuspids  and  molars,  which  would 
present  an  occlusal  surface  of  porcelain  instead  of  gold,  and  which  would 
be  of  more  or  less  urviversal  application. 

As  applied  to  the  second  advantage,  since  so  man\-  who  have  never 
become  skilled  in  soldering,  proceed  with  timidity  toward  the  assemblage 
of  extensive  pieces  of  which  porcelain  facings  form  a  part,  it  is  also 
obvious  that  anv  method  by  which  this  apparejitly  intuitive  dread  may 
be  eliminated  will  be  equally  appreciated. 


4o8 

Whilst  there  is  absolutely  no  danger  of,  nor  excuse  for,  fracturing 
porcelain  facings  in  their  final  assemblage  if  the  proper  precautions,  as 
previously  described,  are  observed,  still  there  is  some  danger  of  dis- 
coloration, and  therefore  there  can  be  no  possible  objection  to  the  pre- 
vious assemblage  of  the  metal  parts  only,  and  the  subsequent  attachment 
of  the  porcelain  to  them,  provided  that  the  retention  of  the  latter  may  be 
secured  in  a  manner  which  insures  at  least  equal  stability  and  perma- 
nency. 

In  this  connection  it  is  claimed  by  the  advocates  of  this  method  of 
construction  that  if  the  base  is  properly  adapted  and  sufficiently  strength- 
ened by  reinforcement,  the  porcelain  teeth  or  facings  attached  thereto 
with  cement  are  far  less  liable  to  fracture  under  the  stress  of  mastication 
than  are  those  which  are  held  so  much  more  rigidly  by  solder.  For  the 
reason  that  the  presence  of  a  layer  of  cement  between  the  metal  and  the 
porcelain  must  diminish  the  force  of  impact,  and  thus  act  as  a  slightly 
yielding  medium,  the  claim  seems  logical. 

The  third  advantage — that  of  the  ease  with  which  repair  may  be 
effected — is  an  equally  important  consideration.  Any  method  which  will 
facilitate  and  expedite  the  repair  of  dental  bridges  will  materially  lessen 
the  burdens  of  the  operator  who  attempts  their  construction,  for  accidents 
will  happen,  and  to  fixed  appliances  perhaps  oftener  than  to  any  other 
form  of  prosthetic  work. 

In  this  connection,  when  this  type  is  used  it  is  well  to  keep  a 
record  of  the  number,  mould  and  shade  of  each  tooth  used  in  each  case, 
for  the  reason  that  in  the  event  of  accident  to  any  tooth  the  replacement 
is  thereby  made  comparatively  easy  by  the  facility  with  which  the  proper 
selection  may  be  made,  after  which,  grinding  to  fit  and  mounting  with 
cement  will  constitute  the  requirements,  and  may  be  effected  without 
delay. 

Davis  Crowns. 

The  Davis  Crowns,  which  are  well  adapted  to  the  construction  of 
bridges  of  this  type,  offer  a  means  of  obtaining  splendid  results  from  the 
combined  viewpoints  of  beauty,  strength  and  hygienic  properties. 

Their  use  is  indicated  in  the  construction  of  both 

Indications.  anterior   and   posterior  bridges,   and   for  abutments 

as  well  as  dummies,  in  that  class  of  cases  where  the 

length  of  the  crowns  of  the  remaining  natural  teeth,  and  the  amount  of 

absorption  where  teeth  are  missing,  will  admit  of  their  application  without 

excessive  grinding. 


409 

They    would    be    contraindicated,    however,    in 

Contraindications,      cases   where  but  Httle   absorption   has   taken  place; 

where  the  crowns  of  the  remaining  natural  teeth  are 

very  short,  or  where  the  "bite"  is  extremely  close;  and  also  in  cases  of 

excessive  absorption  where  the  neck  of  the  crown  could  not  be  placed  in 

contact  with  the  ridge. 

As  applied  to  the  construction  of  anterior  bridges 

Application  the  roots  should  be  prepared  in  the  prescribed  man- 

tO  Hntcrior  Bridges,    ner  except  that  they  should  be  cut  even  with,   ^r 

slightly  beneath,  the  gum  at  all  points,  and  the  caps 

made  by  the  usual  method,  the  band  being  very  narrow  and  of  22K.  gold, 

or  platinum,  29  or  30  ga.,  and  the  floor  from  30  to  32  ga.     When  the 

caps  have  been  thus  made  and  properly  adjusted  to  the  roots  the  canals 


Fiq.  310. 


should  be  prepared,  the  floors  perforated,  and  the  dowels  fitted  and  then 
soldered.  The  apical  end  of  the  dowel  made  expressly  for  these  crowns, 
or  one  of  iridio-platinum,  may  be  used ;  but  all  surplus  should  be  trimmed 
away  even  with  the  floor  after  soldering. 

After  thus  completing  the  caps    (Fig.  310  A) 
ConstrtlCtion  they  should  be  placed  in  position  on  the  roots  and  a 

Of  JIbtltmcnt  Pieces,    bite  in  wax  and  impression  in  plaster  taken.     When 
the  latter  has  been  prepared  for  separating,  the  in- 
terior of  the  caps  should  be  filled  with  a  thin  film  of  wax,  to  admit  of 
easy  removal  from  the  model,  and  the  model  then  obtained  and  mounted 
upon  the  articulator  with  the  "bite." 

Suitable  crowns  should  now  be  selected  and  ground  to  the  proper 
adaptation  in  so  far  as  the  required  adjustment  is  concerned.  After  this 
it  is  necessary  to  grind  away  from  the  hase  enough  to  admit  of  sufiicient 
thickness  of  gold  to  reinforce  the  cap  and  adequately  support  the  crown, 
and  then  slightly  hollow  out  the  approximal  surface  presenting  toward 


410 

the  dummies  so  as  to  accommodate,  and  give  finishing  line  for,  an  exten- 
sion of  the  backing  toward  the  contact  point.  (Fig.  310  B.)  This  affords 
a  greater  soldering  surface  and  admits  of  filling  in  the  space  between 
the  teeth  in  assembling,  thus  insuring  a  greater  degree  of  strength  and 
a  much  cleaner  fixture  when  completed. 

When  the  crowns  are  thus  prepared,  backings  of  32  ga.  22  K.  gold 
should  be  closely  adapted  to  the  base  and  approximal  sides,  which  may  be 
done  best  by  swaging  directly  to  the  tooth  itself.  To  accomplish  this  fill 
one  of  the  rings  of  any  cylinder  and  soft  rubber  plunger  swaging  device 
with  softened  dental  lac,  or  modeling  compound,  and  force  the  crown 
down  in  it  as  illustrated  in  Fig.  311  A.  When  this  is  hard,  trim  to  expose 
the  surfaces  previously  ground ;  adjust  the  dowel  made  for  this  type  of 


crown  with  the  solder  resting  firmly  in  place  in  the  crown ;  perforate 
the  disc  of  gold  and  place  it  over  the  dowel  (Fig.  311  B)  ;  adjust  to  cylin- 
der, insert  soft  vulcanite  plunger  and  swage  (Fig.  311  C). 

After  swaging,  trim  away  surplus  gold  to  proper  outline,  burnish 
down  close  to  crown,  and  then  solder  the  dowel  to  the  backing.  The 
proper  relation  will  be  sustained  by  the  fit  of  the  backing  to  the  shoulder 
of  the  dowel,  but  in  uniting  them  only  a  small  quantity  of  solder  should 
be  used,  and  care  must  be  exercised  to  prevent  it  from  flowing  beyond 
the  shoulder  on  that  side  of  the  backing  which  is  adapted  to  the  crown. 
This  may  be  avoided  by  previously  coating  the  surface  mentioned  with  a 
thin  solution  of  whiting. 

The  surplus  apical  end  of  this  dowel,  which  is  now  not  needed,  should 
be  cut  down  close  to  the  surface  of  the  l)acking,  and  the  latter  then  placed 
in  position  on  the  crown,  and  both  adjusted  to  proper  relation  with  the 
cap  on  the  model. 


411 

This  relation  between  the  backing  and  the  cap  should  now  be  sus- 
tained with  hard  wax,  and  the  whole  then  gently  removed  from  the  model, 
and  the  joint  between  the  two  well  filled  with  wax.  The  crown  may 
now  be  carefully  detached  and  the  cap  and  backing  invested,  and  this 
subsequently  trimmed  in  such  manner  as  to  expose  the  entire  joint  (Fig. 
312).  If  the  interior  of  both  pieces  are  well  filled  with  investment  ma- 
lerial,  and  the  investment  is  then  trimmed  as  indicated,  no  difficulty  will 


Fig.  312. 

be  experienced  in  completely  filling  the  joint  with  at  least  20  k.  solder, 
thus  completing  the  construction  of  the  abutment  pieces  (Fig.  313).  If 
the  cap  is  made  altogether  of  platinum  as  a  means  of  precluding  the 
possibility  of  fusing  it  in  soldering,  the  band  may  be  entirely  covered 
with  solder  in  uniting  the  pieces,  if  care  is  exercised  to  have  it  freely 
exposed,  clean,  and  properly  fluxed. 


Fig.   313. 


When  the  abutment  pieces  are  thus  finished  they, 

Construction  of        with  the  crowns  in  place,  should  be  adjusted  to  the 

Dummies.  model  and  the  dummies  then  prepared.    Except  that 

the  base  of  the  crown  should  be  ground  to  fit  the 

model  as  closely  as  possible,  and  that  both  approximal  sides  should  be 

hollowed  out,  the  details  incident  to  obtaining  the  adaptation  of  the  back- 


412 

ing,  and  the  adjustment  of  the  lower  portion  of  the  dowel  to  it,  for  dum- 
mies, are  identical  with  the  procedure  described  for  the  abutment  pieces. 

To  facilitate  the  final  assemblage  on  the  model, 

Jlsscmbling.  cover  it  between  the  abutment  crowns  with  tin  foil 

and  then  sustain  the  relation  of  the  parts  with  hard 

wax,  after  which  the  porcelain  crowns  may  be  removed  and  the  metal 

parts   then   easily   detached   from  the  model   and  invested  as   shown   in 


Fiq.  31  a. 


Fiq.  3/5. 


Fig.  314.  In  soldering,  care  should  be  exercised  to  completely  fill  the 
joints  between  the  parts,  and  to  so  reinforce  the  base  which  supports  the 
dummies  as  to  insure  strength.  When  the  soldering  has  been  completed 
the  case  should  be  first  properly  finished  and  polished,  and  the  crowns 
then  mounted  with  cement  (Fig.  315). 

In  a  somewhat  modified  and  much  more  simpli- 

Tfpplication  to         fit?d   form  the  same  principles  are  applicable  to  the 

Posterior  Bridges.       construction  of  bridges  involving  the  posterior  teeth 

in    which   application   the  process   is   known   as   the 

Davis-Townsend  method. 


C^ 


Ficj. 


3/6. 


This  method  differs  from  the  former  only  in  that 
Davis-townscnd        ca/).?  or  boxes  of  gold  about  30  ga.,  which  accurately 
method.  fit  the   base  of  the  bicuspid  and  molar  crowns   are 

provided  by  the  manufacturer,  or  may  l)e  made  (Fig. 
316),  and  that  they  are  designed  to  be  used,  mainly,  as  dummies,  in  con- 
junction with  any  type  of  crown  or  abutment  piece. 


413 

In  the  construction  of  bridges  by  this  method  the  abutment  pieces 
should  be  completed  first,  and  the  bite  and  impression  taken  with  them 
in  position.  When  the  model  has  been  obtained  and  mounted  on  the 
articulator  these  gold  caps  should  first  be  selected,  and  afterward  the 
crowns  which  will  fit  into  them. 

The  caps  and  crowns  together  should  then  be  ground  to  the  required 
and  proper  adaptation  to  each  other,  to  the  model  and  to  the  occlusion, 
after  which  the  gold  should  be  carefully  burnished  around  the  edges  of 
each  separate  crown.  They  should  then  be  properly  assembled  on  the 
models  and  the  relation  of  the  gold  caps  securely  sustained  with  hard 
wax.  The  crowns  should  then  be  removed  and  the  spaces  between  the 
caps  filled  with  wax,  when  the  piece  may  be  carefully  detached,  invested 


f/q.  317. 


and  soldered,  following  the  same  detail   recommended  in  the  preceding 
method. 

In  favorable  cases  where  a  good  selection  of  these  crowns  may  be 
made,  the  procedure  is  simple  and  expeditious,  and  the  results  gratifying 
(Fig.  317). 


Brewster's  Bridge  CeetD. 

Another  type  of  porcelain  tooth  designed  especially  for  bicuspid  and 
molar  dummies,  and  to  be  used  in  the  manner  indicated  in  the  preceding 
method,  is  manufactured  by  the  Brewster  Dental  Co.,  of  Chicago.  The 
principle  involved  in  this  tooth  differs  from  the  original  "tube"  tooth, 
Davis  Crown,  and  similar  types,  in  that  the  lingual  surface  is  not  so  deep 
ccrvico-occlusally,  thus  giving  it  a  greater  range  of  adaptability  to  the 
varied  conditions  of  absorption  and  occlusion,  and  in  that  the  dowel  enters 
the  porcelain  at  such  an  angle  as  to  admit  of  considerable  grinding  and 
yet  always  ofifer  a  maximum  degree  of  strength. 


414 

Because  of  the  opportunities  for  obtaining  the 
Tndications.  combined    requirements    of    strength    and    cosmetic 

effect,  the  use  of  these  teeth  is  more  or  less 
generally  indicated  whenever  the  above  conditions  are  at  all  favorable  to 
porcelain,  in  bridges  involving  the  posterior  teeth  where  gold  is  to  be  used 
in  the  construction  of  the  abutment  pieces  and  in  the  assemblage,  and 
yet  where  it  is  desirable  to  avoid  its  display. 

Indeed,  it  would  seem  that  this  or  a  similar  type  of  tooth  would 
eventually  largely  supersede  the  porcelain  facing  and  gold  cusps  as  sub- 
stitutes for  those  teeth  within  the  range  of  vision,  and  that  their  useful- 
ness and  more  general  application  will  increase  in  propcrtion  as  the 
variety  of  moulds  and  colors  are  extended. 


Ficj.  318. 


In  the  application  of  these  teeth  the  abutment 
Jlp^lication.  pieces   should  first  be  completed  and  a  model  with 

them  in  place  thereon  obtained  and  mounted  on  the 
articulator.  The  teeth  should  then  be  selected  and  ground  to  the  proper 
adaptation  to  the  requirements  of  contact  with  the  model,  and  of  occlu- 
sion, being  careful,  however,  to  also  allow  a  slight  space  to  exist  between 
each  tooth,  and  between  them  and  the  abutment  pieces.  This  precaution 
is  necessary  as  a  means  of  providing  for  the  shrinkage  of  the  solder  in 
assembling  the  backings,  and  of  thus  admitting  of  the  replacement  of  the 
facings  after  the  parts  have  been  united. 

Backings  of  pure  gold  from  30  to  32  ga.  should  then  be  closely 
adapted  to  the  entire  lingual  surface  of  each  tooth,  which  may  be  done 
by  swaging,  as  previously  described  or  by  burnishing,  if  preferable,  and 
to  better  protect  the  cusps  should  be  allowed  to  slighth'  overlap  upon 
the  lingual  surface  at  this  point  (Fig.  318). 


415 

When  the  backings  are  thus  properly  adapted,  they  should  be  per- 
forated to  accommodate  the  dowel.  This  can  be  done  to  the  best  advan- 
tage with  a  punch  the  same  size  and  shape  as  the  dowel,  or  with  a  small 
round  bur,  but  in  either  instance  care  should  be  exercised  to  avoid  turn- 
ing an  edge  of  the  perforation  down  into  the  socket  in  the  tooth,  as  that 
precludes  the  ready  separation  of  the  dowel  and  backing  from  the  tooth. 

A  piece  of  the  iridio-platinum  dowel  with  serrated  sides,  which  is 
made  expressly  for  these  teeth  and  which  accurately  fits  the  socket  (Fig. 
319  A),  should  then  be  grasped  firmly  with  pliers  and  gently  forced 
through  the  backing  and  into  the  full  depth  of  the  socket  (Fig.  319  B). 
This  relation  should  now  be  securely  sustained  with  hard  wax  until  the 
dowel  and  backing  together  may  be  removed   from  the  tooth,  invested 


Ficj.  220. 


and  soldered.  The  detachment  of  the  porcelain  tooth  from  its  backing 
may  be  facilitated  by  sealing  the  end  of  a  short  stick  of  hard  or  sealing 
wax  to  the  cusps  of  the  tooth  just  previous  to  separating  them. 

As  strength  in  the  metal  superstructure  is  a  very  important  feature 
in  the  use  of  these  teeth,  the  backing  should  be  well  reinforced  at  this 
time,  and  particularly  around  its  linguo-occlusal  edge  as  a  means  of 
boxing  up  the  lingual  cusps,  and  of  thus  insuring  adequate  support  to 
them  (Fig.  319  C),  and  this  should  be  done  with  a  liberal  use  of  22  or 
20  K.  solder,  so  that  it  may  not  be  re-fused  in  the  final  assemblage. 

When  this  has  been  accomplished  the  backings  should  be  cleaned  in 
the  acid  bath,  adjusted  to  position  on  the  teeth,  and  both  then  properly 
assembled  on  the  model.  After  securely  uniting  the  metal  parts  with  hard 
wax,  the  teeth  should  be  carefully  removed  therefrom  and  the  backings 
and  abutment  pieces  then  invested.     If  investment  material  sufficient  to 


4i6 


securely  hold  the  parts  together  be  used  at  this  time,  and  the  model  sub- 
sequently trimmed  away  until  the  under  surface  of  backings  is  freely 
exposed,  no  further  investment  will  be  required. 

As  a  means  of  insuring  a  maximum  degree  of  strength  in  the  final 
assemblage  of  the  various  parts  a  piece  of  round  iridio-platinum  wire 
from  14  to  16  ga.  should  be  fitted  over  the  center  of  the  backings  from 
one  end  to  the  other,  after  which  the  case  may  be  heated,  and  the  solder- 
ing completed  with  18  K.  solder,  when  it  should  be  finished  and  polished 
and  the  teeth  then  mounted  with  cement. 

Teeth  which  are  slight  variations  of  the  same 

Uariations.  principle  are  also  manufactured  and  may  be  used  for 

anterior  teeth,  on  "saddle"  bridges  where  the  bite  is 

exceedinglv  or  moderately  close,   in  either  "fixed"  or  removable  struc- 


^^K 


tures,  and  as  posterior  teetji  for  the  lower  arch  where  only  the  occlusal 
surface  is  desired  in  order  that  "open"  or  "self-cleansing"  spaces  between 
them  anfl  the  gum  may  obtain  (Fig.  320).  Typical  cases  showing  the 
application  of  these  teeth  to  bicuspid  and  molar  dummies  are  illustrated 
in  Fig.  321. 


Cbe  Boos  method. 

While  several  methods  of  applying  the  removable  or  replaceable 
principles  to  the  ordinary  long-pin  flat  back  teeth,  or  even  to  vulcanite 
teeth,  have  been  devised,  the  one  known  as  the  Boos  method  manufac- 


417 


tured  b}'  the  Iowa  Dental  Specialty  Co.  is  undoubtedly  the  most  simple, 
complete  and  practicable  yet  presented.  In  a  way  this  system  is  some- 
what similar  to  that  advocated  b;-  Dr.  Emory  A.  Bryant,  of  Washington, 
which  has  been  previously  described  in  its  application  to  crown  work,  but 
it  is  a  decided  improvement  thereon  because  in  the  employment  of  Dr. 
Bryant's  method  the  pins  are  allowed  to  remain  at  right  angles  to  the 
long  axis  of  the  facing,  thereby  causing  considerable  bulk  cr  thickness 
of  backing  immediately  over  them. 

Thus  wdien  applied  to  the  six  anterior  teeth — where  both  of  these 
methods  are  most  generally  indicated — an  unnecessary  thickness  Avould 
so  often  interfere  with  the  occlusion  as  to  materially  limit  the  class  of 
cases  in  which  the  method  would  be  applicable. 


a 


FJ(J.  323. 


In  the  Boos  method,  however,  this  objectionable  feature  has  been 
eliminated  and  even  a  more  secure  attachment  of  the  facing  is  obtained, 
and  therefore  when  confined  to  the  six  anterior  teeth  the  range  of  appli- 
cation is  more  extensive. 

Another  highly  important  advantage  is  that  the  backing  is  made  to 
fit  the  tooth.  For  this  reason  the  method  is  applicable  to  any  form,  size 
or  make  of  tooth,  which,  as  compared  with  the  necessarily  more  or  less 
limited  selection  of  facings  offered  by  the  manufacturers  of  other  special 
forms  of  removable  teeth  is  much  in  its  favor. 

It  is  therefore  apparent  that  this  method  is  more 
Tndkations.  or  less   generally   indicated   whenever  it   may   seem 

desirable  to  employ  removable  or  replaceable  teeth, 
for  abutment  pieces  as  well  as  dummies,  in  the  construction  of  anterior 
bridges ;  but  the  necessity  for  using  gold  cusps  when  applying  the  method 
to  bridges  involving  the  posterior  teeth  practically  limits  it  to  the  six  or 
possibly  eight  anterior  teeth. 

In  the  application  of  this  method  all  of  the  fac- 

Jlpplication.  iiigs  for  both  crowns  and  dummies  should  be  selected 

and  ground  to  the  required  adaptation.     The  pins 


4i8 

of  each  tooth  should  then  be  adjusted  to  the  proper  holes  of  correspond 
ing  distance  in  the  "punch-plate"  which  accompanies  the  system  (Fig. 
"^22,  a).  After  ascertaining  which  set  of  holes  accommodates  the  pins 
the  facing  should  be  removed  and  a  backing  of  about  32  ga.,  pure  gold 
or  platinum,  cut  somewhat  larger  than  the  tooth,  then  placed  between 
the  blades  of  the  punch-plate  (Fig.  322  b)  and  slots  punched  in  it  by 
means  of  the  "press"  which  is  also  a  part  of  the  system. 

When  so  prepared,  the  backing  is  then  removed  and  placed  in  posi- 
tion on  the  facing,  with  the  pins  resting  on  one  or  the  other  edge  of  the 


slots  in  accordance  with  the  direction  in  which  they  are  to  be  bent.  If 
this  is  rootwise,  which  is  usually  the  preferable  direction  in  order  that 
the  incisal  end  of  the  backing  may  be  as  thin  as  possible,  they  should  rest 
against  the  cervical  edge  of  the  slots  (Fig.  323  a). 

With  the  backing  held   in  this  relation  it  should  be  burnished  or 
swaged  with  any  of  the  swaging  devices  to  a  perfect  adaptation,  and 


Ficj.  325. 


F/cj.  326. 


then  trimmed  to  the  outline  of  the  facing.  The  next  step  is  to  construct 
a  cover  piece  which  will  form  a  box  for  the  reception  of  the  pins  and 
protect  the  slots  from  solder.  This  is  formed  by  swaging  between  dies 
which  correspond  with  the  distance  between  the  slots,  the  proper  ones 
being  selected  from  a  set  of  three  which  are  also  a  part  of  the  system 
(Fig.  323  B). 

This  should  then  be  properly  adjusted  to  position  on-  the  lingual 
side  of  the  backing,  but  as  the  raised  places  are  purposely  made  longer 
than  the  slots,  in  order  to  accommodate  the  ends  of  the  pins  when  bent, 
the  cover  piece  must  be  so  placed  in  its  relation  to  the  backing  as  to  have 


419 

the  extra  space  present  toward  the  direction  in  which  the  pins  are  to 
be  bent.  Thus  if  the  pins  are  bent  rootwise  the  extra  space  must  be  in 
this  direction  (Fig.  324),  while  if  to  be  bent  toward  the  incisal  end  the 
reverse  relation  is  required. 

When  the  two  are  so  adjusted  they  should  be  held  securely  in  place 
with  small  pointed  pliers,  the  immediate  ends  of  which  are  bent  at  right 
angles  (Fig.  325)  and  soldered  with  a  small  piece  of  2.2  K.  solder. 

The  pins  should  now  be  bent  until  their  ends  will  engage  in  the 
space  between  the  combined  box  and  backing  thus  formed,  which  may 
be  easily  accomplished  by  placing  the  facing  in  the  "tooth  holder"  and 
then  using  a  suitable  instrument  (Fig.  326).  If  the  pins  are  too  long  to 
enter  after  being  bent,  their  ends  may  be  cut  off  until  the  facing  slips 
easily  to  place. 


Fiq.  327. 


Fitj.  328. 


Facings  and  backings  should  now  be  adjusted  to  position  on  the 
model  and  the  relation  between  the  backings  securely  sustained  with  hard 
wax,  after  which  the  facings  should  be  carefully  removed  and  the  aper- 
ture for  the  accommodation  of  the  pins  iiUed  zvith  tnoistened  zvhiting  as  a 
means  of  precluding  the  possibility  of  subsequently  filling  this  with 
solder. 

The  case  should  now  be  invested  and  soldered,  and  then  finished, 
after  which  the  facings  may  be  attached  wath  cement  and  the  piece 
mounted.  A  t\pical  case,  including  even  the  bicuspids,  to  which  the  prin- 
ciple is  also  applicable,  is  illustrated  in  Fig.  327. 

KoacD's  **meagelock"  Bridge  CmD, 


The  type  of  removable  or  replaces  Die  tooth  devised  by  Dr.  F.  E. 
Roach,  of  Chicago,  and  known  as  the  "Wedglock,"  is  another  of  the 
several  forms  designed  to  be  used  in  this  manner,  but  in  this  tooth 
a  specially  prepared  backing  forms  part  of  the  method. 


420 

The   necessity    for   using   them    in   conjunction 

Tndications.  with  gold  cusps  when  apphed  to  the  posterior  teeth, 

however,  practically  limits  the  application  to  the  six, 

or  possibly  eight,  anterior  teeth ;  but  when  confined  in  this  range  and 

when  the  conditions  are  favorable  they  offer  opportunities  for  obtaining 

eminently  satisfactory  results,  perhaps  not  exceeded  by  any  similar  form. 

In  the  application  of  these  teeth  to  bridgework 
JlppHcation.  requirements  are  identically  the  same  as  in  the  con- 

struction of  single  crowns,  which  have  been  previ- 
ously described  in  connection  therewith,  supplemented,  of  course,  with 
those  incident  to  the  use  of  any  of  the  various  forms  of  detachable  teeth. 
A  typical  case  is  illustrated  in  Fig.  328. 


Fia.  329, 


Ficj.  330. 


Steele's  Crown  and  Bridge  Cootb- 

The  principle  involved  in  the  type  of  removable  or  replaceable  tooth 
known  as  "Steele's"  interchangeable  crown  and  bridge  tooth  is  similar 
to  the  one  formerly  called  the  "Mason"  facing,  which  has  also  been 
previously  described  in  connection  with  its  application  to  crown  work. 

This  form  of  tooth,  however,  differs  from  the  "Mason"  in  that  a 
dovetailed  slot  in  the  lingual  surface  of  the  porcelain  tooth  (Fig,  329  A) 
takes  the  place  of  the  platinum  "rib"  of  similar  shape,  which  was  formerly 
used,  thus  eliminating  an  element  of  weakness  which  was  present  in  the 
original  design,  and  also  in  that  a  projection  which  accurately  engages 
into  this  slot  in  the  porcelain  forms  part  of  the  backings,  which  are,  like 
the  immediately  preceding  type,  especially  prepared  for  this  tooth  (Fig. 
329  B), 

If  the  prc-scnce  of  so  large  a  slot  in  the  immediate  center  of  the 
porcelain  does  not  also  prove  to  be  too  great  an  element  of  weakness  by 
increasing  the  liability  of  a  longitudinal  fracture,  the  application  of  this 
form  of  tooth  will  doubtless  be  productive  of  satisfactory  results. 


421 

Like  the  "Roach,"  "Dwight,"  or  any  other  style 
Jlpplicaticn.  oi   tooth    having    specially   prepared   backings,    it   is 

imperative  that  the  surface  of  the  backing  which 
comes  in  contact  with  the  facing  should  be  kept  clean  and  free  from  solder 
during  .ls  adaptation,  and  during  the  subsequent  assemblage  of  the  parts. 
Aside  from  this,  all  of  the  other  requirements  and  precautions  incident 
to  the  application  of  these  teeth  in  a  general  way — which  have  already 
been  mentioned — must  also  be  carefully  observed.  Fig.  330  illustrates 
a  typical  case. 

Uariatlons. 

The  mechanical  versatility  of  the  dental  profession  is  so  frequently 
evidenced  by  the  introduction  of  methods  and  ideas  pertaining  to  the 
construction  of  dental  bridgework  that  it  is  a  difficult  matter  to  keep  pace 
with  and  do  justice  to  all  of  the  various  systems  presented.  And  yet, 
while  those  considered  as  being  the  most  useful  and  applicable  have 
probably  been  properly  classified  in  the  preceding  pages,  many  good  ideas 
may  nevertheless  be  elucidated  in  the  presentation  of  those  deemed  to  be 
perhaps  less  practicable.  Indeed,  in  learning  where,  how,  or  when  not 
to  use  some  methods,  we  may  profit  by  the  possession  of  knowledge 
from  even  the  most  useless  ones.  Although  no  efifort  will  be  made  to 
consider  the  full  range  of  methods,  or  those  which  are  deemed  absolutely 
useless,  still  the  ingenuity  manifested  in  some  warrants  their  consid- 
eration here. 

Cbe  toudue  mctboa. 

A  method  departing  from  the  removable  type  of  construction, 
and    involving   the   employment   of   a   special    form   of   tooth    designed 


f/^.  331. 

for  and  applicable  only  to  bicuspid  and  molar  dummies,  to  be  used 
in  conjunction  with  any  of  the  various  types  of  abutment  pieces,  and 
assembled  by  soldering,  is  known  as  the  Louque  method. 

The  form  of  tooth  embraced  therein  difiters  from  others  in  that  it 
presents  an  all  porcelain  crown  having  a  slightly  concaved  cervical  end 
to  facilitate  its  adaptation  to  the  gum,  or  to  a  saddle,  and  in  that  it  is 


422 

provided  with  a  perforation  extending  laterally  through  its  thickest  part 
from  one  approximal  surface  to  the  other.  This  affords  the  means  of 
attachment  or  assemblage,  and  is  obtained  by  backing  the  tooth  around  a 
thin  platinum  tube  which  remains  as  a  part  thereof  (Fig.  331). 

In  the  application  of  this  method  the  teeth  are 
Jlpplkation.  assembled  by  means   of  passing  a   piece   of   iridio- 

platinum  wire  through  the  platinum-lined  perfora- 
tion, allowing  its  end  to  project  slightly  beyond  the  concaved  surface 
of  the  porcelain  on  each  side,  and  then  perforating  and  burnishing  a  piece 


Fiq.  332. 


of  platinum  foil  over  these  exposed  ends  and  around  the  entire  lingual 
surface  as  a  means  of  forming  a  backing. 

When  backed  up  in  this  way,  and  adjusted  to  position  on  the  model 
the  spaces  between  the  teeth  themselves,  and  the  abutment  pieces  as  well, 
will  be  lined  with  platinum,  thus  forming  a  matrix  and  admitting,  when 
properly  invested,  of  their  subsequent  union  with  solder. 

In  their  final  assemblage  the  investment  mass  should  be  no  larger 
than  necessary,  and  extremely  well  heated  before  attempting  to  solder, 
in  order  that  the  solder  miy  grasp  the  short  projecting  ends  of  the  wire. 
After  observing  these  precautions  the  intervening  spaces  should  then  be 
filled  well  with  solder,  not  permitting  it,  however,  to  flow  over  on  the 
platinum  which  covers  the  lingual  surfaces,  as  this  is  subsequently  re- 
moved in  the  process  of  finishing.  The  principle  of  attachment  and  the 
result  obtained  in  the  finished  piece  are  illustrated  in  Fig.  332. 

While  the  purely  cosmetic  requirements  are  admirably  subserved  in 
the  application  of  these  teeth,  yet  the  possibilities  for  obtaining  strength 
in  the  metal  superstructure  which  must  support  them  appear  to  be  limited, 
and,  when  this  feature  is  combined  with  the  possibilities  of  fracturing 
the  porcelain  in  soldering  which  might  easily  be  caused  by  the  shrinkage 
of  the  solder,  it  would  seem  that,  in  view  of  better  ones,  this  method 
is  of  doubtful  practicability. 


423 

Bryan's  Itletbods. 

For  the  purpose  of  counteracting  lateral  stress  in  the  application  of 
fixed  bridges  the  methods  of  construction  suggested  by  Dr.  L.  C.  Bryan, 
of  Basel,  Switzerland,  may  be  somewhat  novel  and  interesting. 

These  embrace  a  more  radical  use  of  the  principle  of  the  "saddle" 
than  usual,  and  are  recommended  as  being  applicable  to  those  cases 
where  some  support  against  lateral  stress  is  demanded  by  the  stability 
of  the  abutments. 


Fi(^.  333f. 


In  bridges  involving  only  one  side  of  the  arch  where  this  condition 
exists,  support  is  obtained  by  extending  curved  braces  rootwise  upon 
both  the  buccal  and  lingual  sides  of  the  alveoli,  as  high  as  they  may  be 
worn  with  comfort,  and  in  as  close  adaptation  to  the  tissue  as  it  is  possi- 
ble to  place  them  (Fig.  ^SS)- 

Or,  in  cases  where  a  bridge,  or  even  single  crowns,  may  present,  or 
be  required  upon  the  opposite  side  of  the  arch,  this  support  is  obtained 
by  uniting  them  with  a  heavy,  well  adapted,  narrow  saddle  extending 
transversely  across  the  palate  as  illustrated  in  Fig.  334. 

By  the  application  of  either  of  these  methods  it  will  be  observed  that 
support  against  lateral  stress  is  undoubtedly  afforded,  and  while  the  prin- 
ciples involved  may  be  practical  for  temporary  purposes,  or  as  an 
expedient,  it  would  seem  that  the  utility  of  such  a  type  of  construction 
is  questionable  for  the  reason  that  if  the  condition  of  the  supporting  roots 
demanded  such  provisions,  a  ft.rcd  bridge  would  rarely  be  indicated,  and 
that  the  unhygienic  conditions  necessarily  arising  would  be  a  menace  to 
the  comfort  and  health  of  the  wearer. 


424 

Cownsend's  nicfftoa. 

Another  somewhat  novel  but  very  ingenious  method  combining  the 
principles  of  both  fixed  and  removable  bridgework  has  been  suggested 
by  Dr.  E.  L.  Townsend,  of  Los  Angeles,  Cal. 

In  this  combination  type  of  construction  wide  bands  are  first  closely 
adapted  around  the  entire  circumference  of  the  crowns  of  the  supporting 
teeth — without  giving  them  any  preparation  whatever^ — by  means  of  pliers 
designed  for  the  purpose.  When  the  desired  adaptation  has  been  com- 
pleted, the  bands  are  removed  and  soldered.  Gold  dummies  are  now 
made  to  fill  the  space  and  to  occlude,  and  the  whole  is  then  united 
with  solder.    When  nicelv  finished  the  band  and  dummv  on  each  end  are 


Ficj.  335. 

separated  in  such  manner  as  to  leave  shoulder  enough  to  accommodate 
a  small  screw  when  reapproximated,  wdfich  may  be  done  with  a  fine  me- 
chanical saw,  and  through  each  surface  a  hole  is  afterward  drilled  and 
then  threaded.  A  small,  short  screw  is  now  made  and  fitted  into  this, 
and  when  the  adjustment  is  completed  the  band  may  then,  and  by  this 
means,  be  locked  to  place  on  each  tooth  (Fig.  335). 

While  this  method,  of  course,  admits  of  obtaining  an  accurate  fit  to 
the  tooth  without  injury  thereto,  and  of  the  ready  removal  of  the  piece 
at  any  time,  even  though  mounted  with  cement,  still  the  advantages  are 
so  slight  and  the  detail  so  intricate  as  to  limit  its  usefulness. 

Descriptions    of    the    innumerable    methods    of 

Obsolete  anchoring  fixed  bridges  by  means  of  simple  bands, 

Procedures.  projecting  ends  of  bars  resting  in  cavities  which  are 

to  be  filled  after  the  l)ridge  is  mounted,  etc.,  etc.,  are 

purposely  omitted  for  the  reason  that  such  methods  when  compared  with 

modern  procedures  are  not  regarded  as  being  of  practical  value. 


JfssentbUng,  f  ittisbittd,  IHounting  and  Repairing. 


CHAPTER  XXIV. 

As€embling:   Requirements,   Anterior   Bridges,   Posterior   Bridges,    Saddle   Bridges, 

Extensive  Bridges,  Soldering.   Finishing:  Engine  Work,  Lathe  Work. 

Gold  Plating.     Mounting:  Preliminary  Requirements, 

Cement,   Gutta-Percha,    Repairing. 


The  features  and  procedures  incident  to  assembling,  finishing,  mount- 
ing and  repairing  fixed  bridgework  are  of  importance  almost  equal  to 
those  involved  in  the  study  and  application  of  the  foundations,  and 
should  be  observed  in  detail  quite  as  fully  as  any  other  part  of  the  process 
of  construction,  while  it  is  manifest  that  a  knowledge  of  the  last  is  equally 
as  essential. 

J1$$etnbling. 

Although  the  principles  underlying  the  final  assemblage  of  the 
various  separate  parts  which  comprise  the  structure  have  already  been 
more  or  less  carefully  considered  in  the  chapters  on  "Investing"  and 
"Soldering,"  yet,  the  requirements  as  applied  exclusively  to  bridgework 
will,  nevertheless,  be  briefl)'  described. 

When  all  of  the  parts  have  been  completed  to 

K^quircmcntS.         point  of  finishing,  it  is  then  first  necessary  to  deter- 
mine whether  the  case  is  to  be  invested  on  the  model, 
or  detached  therefrom  and  invested  separately,  in  which  decision  one  is 
guided  more  or  less  by  the  size  of  the  piece. 

In  large  bridges  or  those  involving  three  or  more  "abutment  pieces,'' 
the  danger  of  displacing  some  part  or  other  in  attempting  to  remove  it 
from  the  model,  usually  indicates  that  the  safest  procedure  is  to  allow 
it  to  remain  in  situ  thereon. 

This  may  be  done  by  first  securely  uniting  the  various  parts  along 
the  lingual  surface  with  hard  wax,  and  then  further  insuring  the  preserva- 


426 

tion  of  their  proper  relation  by  covering  the  exposed  outer  surfaces  of 
metal  and  porcelain  with  a  thin  layer  of  investment  material  or  plaster. 
(See  Fig.  24.)  When  this  is  hard,  the  case,  model  and  all,  should  be 
removed  from  the  articulator,  and  the  model  trimmed  down  until  only 
enough  of  it  remains  to  hold  the  parts  together.  It  is  then  ready  to 
be  invested.  Even  though  the  model  be  of  plaster  the  small  piece  thus 
remaining  will  in  no  manner  interfere  with  the  process  of  soldering  if  it 
be  completely  covered  with  investment  material. 

In  small  cases  where  there  are  less  than  three  abutment  pieces  it 
may  be  quite  safe,  and  even  preferable,  to  remove  the  parts  from  the 
model,  thus  preserving  it,  and  invest  separately.  When  this  procedure 
seems  desirable  the  abutment  pieces  should  first  be  detached  in  such 
manner  as  to  admit  of  their  accurate  replacement,  then  properly  read- 
justed to  position,  the  dummies  also  arranged  in  their  correct  place,  and 
the  relation  sustained  with  hard  wax,  when  all  may  be  removed  and 
invested. 

Previous  to  the  final  arrangement  on  the  model,  if  the  surface  be- 
tween the  "abutment  pieces"  be  covered  with  tin  foil  to  prevent  the  hard 
wax  from  clinging  thereto,  the  ready  removal  of  the  parts  after  being 
thus  temporarily  assembled  will  be  greatly  facilitated. 

An  observation  of  the  following  additional  precautions  will  con- 
tribute much  to  the  successful  investment  of  the  case,  whether  it  be  large 
or  small. 

First,  all  parts  to  be  exposed  after  investing  should  previously  be 
well  covered  with  wax  as  a  means  of  indicating  the  surfaces  which  are 
to  be  ultimately  exposed,  and  of  keeping  them  perfectly  clean. 

Second,  the  interior  of  all  "abutment  pieces"  must  he  well  -filled  with 
plaster  or  investment  material  prior  to  investing,  as  a  means  of  pre- 
venting the  concentration  of  excessive  heat  which  may  fuse  them. 

Third,  the  investment  should  be  trimmed  down  until  no  surplus  be- 
yond the  actual  requirements  remains,  and  until  all  of  the  wax  is  ex- 
posed. This  in  turn  facilitates  the  free  exposure  of  the  metal  parts,  and 
diminishes  the  degree  of  heat  required  to  solder. 

Fourth,  the  wax  should  be  carefully  removed  with  a  small  sharp 
pointed  instrument,  and  any  overhanging  edges  of  the  investment  then 
trimmed  away  until  the  metal  surfaces  of  both  "abutment  pieces"  and 
dummies  are  freely  exposed.  Strength  in  the  investment  should  be  ob- 
tained from  the  under  side  in  order  to  admit  of  this,  and  thus  facilitate 
and  expedite  the  process  of  heating  up  and  soldering. 

I'iflh,  the  rer|uircments  of  contact  between  the  parts;  of  adaptation 
in  the  event  of  the  use  of  connecting  bars  or  wedges  for  preserving  the 


427 

proper  relation  and  insuring  strength ;  of  flnx,  'and  of  preventing  the 
solder  from  flowing  where  it  is  not  wanted,  should  be  observed  before 
the  case  is  heated. 

In  the  assemblage  of  bridges  involving  the  six 
interior  Bridges.  anterior  teetlr  it  is  always  necessary  to  observe  some 
means  of  insuring  adequate  strength  in  the  union, 
and  of  preserving  the  individuality  of  the  incisor  facings  by  preventing 
the  complete  union  of  their  backings  from  cervical  to  incisal  end.  In- 
deed, nothing  so  enhances  the  appearance  of  anterior  bridges  assembled 
with  gold  as  avoiding  a  show  of  gold  between  the  facings. 

While  it  should  first  be  observed  that  the  backings  do  not  come  in 
direct  contact  hctivecn  the  pins  and  the  incisal  ends  (which  should  of 
course  be  noted  before  the  case  is  invested)    this  particularly  desirable 


F,cj.33d. 


feature  may  be  best  obtained  by  filling  in  between  the  incisal  ends  of  the 
backings  before  the  case  is  heated,  with  a  thin  solution  of  whiting.  This 
may  easily  be  done  with  a  small  pointed  brush  and  will  accomplish  the 
purpose  by  preventing  the  solder  from  running  into  the  joint  and  uniting 
the  backings  at  these  places. 

As  such  a  procedure  will  usually  leave  but  a  very  small  portion  of 
the  backings  in  contact,  and  to  be  united,  extreme  care  must  be  observed 
to  obtain  the  necessary  strength  in  the  assemblage.  This  may  be  insured, 
however,  by  fitting  a  piece  of  round  iridio-platinum  wire  about  i8  gauge, 
directly  over  or  immediately  under  the  ])ins,  and  across  the  backings 
from  cuspid  to  cuspid,  before  the  case  is  heated,  and  then  allowing  the 
solder  to  flow  only  over  and  around  this  wire  from  one  end  to  the  other. 
(Fig.  336.)  Ample  strength,  and  a  better  lingual  contour  will  then  result, 
and  the  cosmetic  requirements  will  at  the  same  time  be  highly  subserved. 

The  former  practice  of  placing  thin  pieces  of  ;/;;V(7  between  the 
incisal  ends  of  the  backings  for  this  purpose  is  objectionable  for  the  rea- 
son that  it  is  frequently  attached  to  the  porcelain  by  the  fusion  of  the 


428 

borax,  and  becomes  exceedingly  difficult  to  remove.  Small  pieces  of 
paper  or  cardboard  are  also  used  in  a  similar  manner,  but,  while  the)' 
preserve  a  space  between  the  facings,  they  do  not  prevent  a  union  of  the 
backings. 

No  special  precautions  other  than  those  men- 
POSterior  Bridges.  tioned  are  demanded  in  the  assemblage  of  posterior 
bridges,  except  perhaps  that  the  requirements  of 
strength  and  contour  must  also  always  obtain.  Both  of  these  may  be 
secured  by  using,  in  similar  manner,  an  iridio-platinum  wire  of 
from  14  to  16  gauge,  thus  requiring  less  solder  and  insuring  greater 
strength  and  better  contour.  In  this  connection  it  is  always  desirable 
to  carry  as  small  a  quantity  of  solder  to  the  melted  state  at  one  time  as 
possible,  in  order  to  minimize  shrinkage,  and  the  value  of  the  use  of  wire 
in  this  manner  is  therefore  apparent. 

The  use  of  wire  as  suggested  will  also  be  found 
Saddle  BtidgCS.  particularly  advantageous  in  the  assemblage  of 
saddle  bridges  because  of  the  greater  space  between 
the  saddle  and  the  cusps  which  must  be  filled  in  order  to  have  the  desired 
lingual  contour  obtain.  Globules  of  scrap  gold  may  also  be  used,  or,  if 
desired,  those  of  copper  or  german-silver,  provided  they  are  not  melted 
so  as  to  become  alloyed  with  the  solder,  and  also  provided  that  they  are 
completely  covered  with  solder  so  as  not  to  be  exposed  in  finishing. 

Because  of  the  shrinkage  of  solder,  and  of  the 
extensive  Bridges.      fact  that  it  is  not  always  possible  to  entirely  over- 
come   or    control    it,    the    assemblage    of    extensive 
bridges    involving    all    or    nearly    all    of    the    denture,    may    invariably 
be  best  accomplished  by  first  dividing  them  and  investing  and  soldering 
in  sections,  and  then  subsequently  uniting  the  sections. 

In  cases,  for  instance,  which  extend  from  the  molars  on  one  side  to 
those  on  the  other,  if  soldered  all  at  one  time  the  shrinkage  may  be  so 
great,  owing  to  the  curvature,  as  to  preclude  the  subsequent  adjustment 
of  the  piece  to  its  position  in  the  mouth.  Indeed  in  such  cases  this  will 
be  the  usual  result  unless  proper  precautions  are  observed. 

After  the  assemblage  on  the  model,  however,  if  it  be  divided  at  the 
median  line  and  each  lateral  half  invested  and  soldered  separately,  no 
difficulty  will  be  experienced.  Each  piece  may  then  be  finished,  and 
adjusted  to  position  in  the  mouth,  when  an  impression  in  plaster  should 
be  taken.  This  should  be  filled  with  investment  material  and  the  model 
obtained,  after  which  it  may  be  trimmed  small  and  invested,  and  the  two 
pieces  then  united  in  the  center,  when  it  will  be  found  that  they  will  go 
readily  to  place. 


429 

All    of   the    precautions    incident    to    soldering 
Soldering.  which  have  been  previously  mentioned  must  be  ob- 

served, but  by  way  of  emphasis  it  should  be  remem- 
bered that  no  efifort  to  accomplish  this  procedure  should  ever  be  attempted 
until  tlie  case  has  been  allowed  to  remain  on  the  burner  sufficiently  long 
to  become  thoroughly  heated.  If  the  surfaces  of  metal  and  solder  have 
then  been  properly  fluxed,  but  little  effort  will  be  required,  and  the 
ordinary  combination  mouth  blow-pipe  will  answer  the  purpose.  While 
compressed  air  may  be  used  by  skilled  hands,  still  it  is  easier  to  regulate 
and  control  the  heat  with  the  mouth  blow-pipe,  which  is  therefore  mani- 
festly more  reliable  and  safer. 

In  the  management  of  a  large  quantity  of  solder  such  as  is  required 
in  assembling  bridgework  the  procedure  may  be  greatly  facilitated  by 
first  cutting  the  solder  into  good  sized  pieces,  and  then  using  the  sharpened 
point  of  an  ordinary  slate-pencil  to  pull,  push  or  guide  the  solder  when 
in  a  plastic  state  to  the  desired  point,  as  recently  suggested,  and,  in  plac- 
ing the  solder,  long  pointed  pliers  may  be  used  with  more  comfort,  of 
course,  than  short  ones.  When  considerable  filling  in  between  the  parts 
is  required,  previously  melting  the  solder  into  various  sized  globules, 
and  then  packing  these  into  the  spaces  before  fusing,  will  also  facilitate 
and  expedite  the  work. 

Tiitlsbing. 

Much  of  the  artistic  effect  to  be  obtained  in  the  construction  of 
dental  bridges  will  depend  upon  the  manner  in  which  the  work  is  finished 
before  mounting  and  many  otherwise  well  constructed  pieces  lack  those 
earmarks  which  stamp  them  as  artistic  productions  simply  because  they 
are  not  properly  finished. 

While  the  finished  bridge  workman  need  not  class  himself,  nor  be 
classed,  as  a  "dental  jeweler,"  still  his  every  piece  of  work  should  never- 
theless be  finished  like  a  piece  of  jewelry,  and  he  is  not  a  "finished" 
workman  nor  even  a  good  goldsmith  unless  it  is. 

This  is  not  altogether  a  purely  cosmetic  requirement  either,  for  the 
manner  in  which  a  piece  of  work  is  finished  will  have  much  influence 
upon  its  hygienic  qualities,  and  therefore  it  is  apparent  that  these  com- 
bined requirements  demand  that  proper  attention  be  given  to  this  part 
of  the  detail  of  construction. 

The  fact  that  the  work  of  some  operators  never  looks  as  well  as  that 
of  others,  of  perhaps  equal  skill,  may  invariably  be  attributed  to  the 
further  fact  that  the  one  will  spend  an  hour,  perhaps,  to  accomplish  that 


430 

which  the  other  would  try  to  do  in  a  few  minutes.  This  time,  however, 
is  by  no  means  wasted  because  well  finished  work  will  not  only  look  better 
at  the  time  when  it  is  mounted,  but  by  being  well  finished  will  ahways 
look  better,  for  the  reason  that  highly  polished  surfaces  of  metal  will 
resist  the  chemical  action  of  the  secretions  more  permanently,  and  will 
also  be  more  easily  kept  clean  and  therefore  will  be  more  hygienic. 

In  the  process  of  finishing  the  first  essential  is 
engine  lUork.  to  subject  the  piece  to  the  acid  bath  and  allow  it  to 
remain  therein  long  enough  to  dissolve  all  particles 
of  flux  and  investment  material  which  may  cling  to  it  after  soldering. 
When  this  has  been  accomplished  the  acid  should  be  thoroughly  removed 
with  water  and  the  piece  then  finished  with  small  thin-edge  carborundum 
stones  used  in  the  engine. 

This  preliminary  process  should  be  continued  until  all  solder  pits 
and  inaccessible  pockets  have  been  more  or  less  obliterated,  and  until 
the  finishing  lines  between  metal  and  porcelain  are  well  defined,  and  all 
of  the  surfaces  contoured  as  desired  and  perfectly  smooth.  Coarse, 
medium,  and  then  fine  emery  or  sand  paper  disks  should  be  used  until  the 
deeper  scratches  are  well  removed,  when  the  piece  is  ready  for  the  lathe. 

As  applied  to  the  work  to  be  done  on  the  lathe 
CatbC  Ulork.  every    observable    scratch    should    first    be    worked 

down  with  a  fairly  thin  felt  wheel  and  moistened 
pumice-stone  until  the  piece  is  ready  to  be  polished,  when  a  stiff  brush 
wheel  and  moistened  whiting,  or  precipitated  chalk,  followed  by  the  soft 
brush,  and  then  by  the  "buffer"  will  result  in  imparting  the  high  degree 
of  finish  which  is  desirable,  and  a  few  minutes  thus  expended  will  be 
productive  of  the  advantages  mentioned. 

Rouge  and  other  jeweler's  polishing  compounds  are  frequently 
recommended,  and  while  not  objectionable  the  polish  obtained  by  the 
proper  use  of  whiting  is  generally  preferable,  and  the  lathe  work  cleaner. 

Nothing   adds  more  to   the  highly   artistic   ap- 
6old  Plating.  pearance,  nor  to  the  permanency  of  the  finish,  than 

to  subject  the  piece  to  the  gold-plating  solution  after 
it  has  been  well  polished.  This  imparts  a  uniform  color  to  the  metal 
parts,  and  a  resistance  to  the  chemical  action  of  the  secretions,  which 
is  not  otherwise  obtainable,  and  will  be  more  or  less  permanent  in  ac- 
cordance with  the  number  of  times  that  the  i)icce  ma\'  be  removed  from 
the  solution,  repolished  with  the  buffer  and  whiting,  and  then  replaced 
therein.  Two  platings  with  a  good  polishing  in  between  them,  however, 
will  usually  suffice. 

While  the  details  pertaining  to  this  particular  phase  of  the  subject 


431 

have  received  a  more  complete  description  elsewhere  (see  page  288),  a 
simple  and  inexpensive  apparatus  to  be  used  in  combination  with  the 
commercial  plug  known  as  the  Teter  Tap,  has  been  suggested  by  Dr. 
C.  S.  Case,  of  Chicago.  In  the  use  of  this  the  current  may  be  taken 
directly  from  the  socket  which  supplies  it  for  illuminating  purposes,  the 
resistance  being  obtained  through  the  use  of  an  eight  candle  power  lamp 
in  serial  connections  therewith. 

Itloutititid. 

Few  of  the  details  incident  to  the  application  of  fixed  bridgework  are 
more  important  than  those  involved  in  properly  and  securely  mounting  it 
in  the  mouth,  and  this  procedure,  therefore,  requires  painstaking  care. 

Preliminary  to  the  final   mounting   it   must   of 
Preliminary  course  always  be  first  ascertained  that  the  piece  goes 

KCiluiremcnts.         readily  and  accurately  to  place,  and  that  the  occlusion 
is  correct. 

In  this  connection  it  not  infrequently  happens  that  some  difficulty 
may  be  encountered  in  adjusting  the  piece  to  its  proper  position  because 
there  may  not  be  perfect  parallelism  between  the  abutments,  w^hich  mav 
not  have  been  noted  in  the  construction  of  the  abutment  pieces,  and 
which  does  not  become  apparent  therefore  until  effort  is  made  to  adjust 
the  assembled  piece. 

Indeed  it  will  sometimes  seem  as  though  a  proper  adjustment  would 
be  quite  out  of  the  question,  until  by  gradually  and  carefully  enlarging 
the  openings  of  the  canals  for  dowel  crowns,  or  by  further  grinding 
away  from  the  interfering  approximal  surface  of  a  posterior  abutment, 
or  both,  the  piece  may  finally  be  slipped  over  and  forced  to  place.  In 
these  instances  extreme  care  and  even  more  than  moderate  patience  may 
be  required,  but  painstaking  persistence  will  usually  result  in  effecting 
the  proper  adjustment. 

When  this  has  been  obtained  the  occlusion  should  be  noted  and  if 
alterations  are  necessary  they  should  be  made  at  this  time  by  removing, 
grinding  and  then  readjusting  until  a  degree  of  accuracy  obtains,  which 
will  insure  comfort  and  usefulness,  and  then  such  surfaces  as  have  been 
ground  should  be  again  polished. 

Because  of  the  discomfiture  which  may  result  from  the  wearing — 
even  temporarily — of  a  bridge  which  does  not  occlude  properlv,  together 
with  the  danger  to  the  porcelain  teeth  or  facings  thereby  oft'ered.  the 
patient  should  under  no  circumstances  ever  be  dismissed  until  the  occlusion 
of  the  piece  has  been  made  perfect,  and  all  undue  stress  relieved. 


432 

While  it  is  permissible  to  finally  and  permanently  mount  all  small 
bridges  as  soon  as  these  requirements  have  been  observed,  in  larger 
cases,  where  two  or  more  abutments  are  involved,  it  is  always  the  best 
practice  to  have  the  patient  wear  the  piece  for  one  or  perhaps  two  da}s 
before  finally  and  permanently  mounting  it.  By  so  doing  the  roots  and 
abutment  pieces  become  adjusted  to  their  proper  relation  with  each 
other  in  such  manner  as  to  greatly  facilitate  the  final  procedure,  and 
better  opportunity  is  thus  offered  for  observing  and  remedying  any 
slight  imperfections  which  may  exist.  Unless  mounted  with  some  tem- 
porary medium,  however,  such  as  "temporary  stopping,"  it  is  never  advis- 
able to  allow  the  patient  to  wear  a  bridge  longer  than  two  days,  because 
in  this  time  it  will  become  foul,  and  get  loose,  and  the  accuracy  of  the 
adaptation  of  the  "abutment  pieces"  may  thus  become  destroyed  by  the 
mobility. 

When  these  preliminary  requirements  have  been  observed,  and  the 
ready  adjustment  of  the  piece  is  thereby  insured,  both  it  and  the  abut- 
ments should  then  be  prepared  for  the  final  and  permanent  mounting. 

In  typical   bridges   if   cement,   which   is   recog- 
Cemcnt.  nized  as  being,  perhaps,  the  most  permanent  medium, 

is  to  be  employed  the  first  precaution  necessary  is 
to  observe  some  means  of  precluding  or  diminishing  the  attending  dis- 
comfort which  results  from  the  irritating  influence  particularly  of  the 
oxyphosphate  cements.  This  may  be  accomplished  by  the  topical  applica- 
tion of  a  2%  solution  of  cocaine  around  the  abutments,  or  by  painting 
the  interior  surfaces  of  the  bands  with  95%  carbolic  acid,  and  forcing 
the  piece  to  place  and  allowing  it  to  remain  for  a  few  moments,  as  pre- 
viously recommended  in  connection  with  the  mounting  of  crowns. 

The  abutment  pieces  should  then  be  thoroughly  dried  with  hot  air, 
and  the  dowels  covered  with  gutta-percha,  temporary-stopping,  or  var- 
nish, in  accordance  with  the  requirements  in  this  connection  which  have 
also  been  previously  mentioned  in  connection  with  crown  work. 

When  the  piece  is  thus  properly  prepared,  the  abutments  should 
be  rendered  aseptic  by  the  free  use  of  absolute  alcohol,  and  subse- 
quently dried  with  hot  air.  As  a  means  of  keeping  them  dry  during 
the  procedure  the  checks  or  tongue  should  be  kept  away,  and  for  this 
purpose  the  non-absorbent  aseptic  cotton  rolls  prepared  by  Johnson  and 
Johnson  will  be  found  particularly  useful,  and  these  may  in  many  in- 
stances be  lield  in  ])lacc  witli  the  clamijs  designed  by  them  for  the  purpose. 

(T^ig-  337-) 

The  cement  should  now  be  mixed  (preferably  by  an  assistant)  to  a 
thick  creamy  consistency,  and  the  canals  first  filled,  and  then  the  abut- 


433 

ment  pieces,  when  the  bridge  may  be  gently  and  gradually  forced  to  place. 
As  soon  as  the  adjustment  has  been  made  the  patient  should  be 
immediately  required  to  close  the  mouth  firmly  in  order  that  the  operator 
may  ascertain  that  the  proper  relation  has  been  obtained,  and  that  the 
occlusion  is  correct,  and  when  it  is  found  to  be  as  desired,  a  firm  closure 
should  be  maintained  for  a  period  of  five  or  ten  minutes,  or  until  the 


f/(j.  337. 


cement  may  have  had  opportunity  to  become  fairly  well  crystallized 
before  the  piece  may  be  subjected  to  the  influence  of  stress  in  a  lateral 
direction. 

After  the  lapse  of  a  few  minutes  for  this  purpose,  a  more  complete 
crystallization  may  then  be  hastened  by  a  spray  of  hot  water,  by  hot  air, 
or  by  any  of  the  electrical  heating  devices,  when  all  of  the  surplus  should 
be  carefully  removed. 

To  insure  the  thorough  removal  of  all  surplus  and  thus  avoid  the 
subsequent  irritation  which  may  be  induced  by  hidden  particles,  silk 
floss  should  be  used  between  and  around  the  abutment  pieces  in  such 
manner  as  to  dislodge  any  nodules  which  may  remain  under  or  within 
the  free  margin  of  the  gum,  after  which  the  topical  application  of  campho- 
phenique  as  a  healing  agent  will  be  found  beneficial. 

In  the  event  of  the  previous  filling  of  the  root  canals  of  an  abutment, 
by    another   operator   and   at   another   time,   remote   or    otherwise,    they 


434 

should  nevertheless  always  be  closely  examined  by  the  one  who  constructs 
and  permanently  mounts  the  bridge,  for  only  by  this  means  may  it  be 
ascertained  that  they  are  well  filled,  and  this  is  imperative  for  the  reason 
that  one  thus  assumes  the  responsibility  for  conditions  which  may  have 
to  do  with  the  permanency  and  comfort  of  the  piece. 

While  several  methods  and  appliances  for  excluding  moisture  during 
the  mounting  of  fixed  bridges  with  cement  have  been  devised,  none  of 
them  serves  the  purpose  better  than  the  one  mentioned,  nor  is  any  other 
so  universally  applicable. 

In  the  mounting  of  saddle  bridges  with  cement 

Saddle  Bridges.        the  greatest  possible  care  must  be  exercised  in  order 

to  preclude  forcing  the  cement  in  between  the  saddle 

and  the  tissue,  and  to  avoid  the  irritation  which  will  result  therefrom  after 

crystallization. 

Indeed,  as  a  general  rule,  it  is  so  difficult  to  provide  against  this 
with  any  degree  of  certainty,  that  it  is  invariably  the  best  practice  to 
mount  such  bridges  with  gutta-percha. 

Where  cement  is  used,  however,  the  possibilities  of  subsequent  irrita- 
tion may  be  more  or  less  largely  overcome  by  first  coating  the  surface  of 
the  saddle  with  gum  acacia  dissolved  in  water,  as  suggested  by  Dr.  G. 
W.  Whitfield.  This  hardens  more  or  less  readily,  and  the  cement  will 
then  be  forced  out  from  between  the  saddle  and  the  tissue,  hence  any 
adhesion  of  it  to  the  surface  of  the  saddle  is  thus  prevented.  It 
may  also  be  advantageous  to  place  the  immediate  center  of  a  piece  of 
fine  waxed  silk  floss  of  considerable  length  over  the  saddle,  before 
mounting,  and  then  subsequently  removing  any  cement  by  drawing  this 
backward  and  forward  across  the  saddle  from  one  end  to  the  other, 
while  the  patient  maintains  a  firm  inclosure  upon  the  bridge.  Aside  from 
these  or  similar  precautions  the  procedure  as  above  mentioned  should 
be  observed  in  detail. 

The  use  of  gutta-percha  as  a  mounting  medium 

Outta-Pcrcba.  for  all  types  of  fixed  bridgework  is  becoming  more 

and   more   general   in   proportion   as  its   advantages 

are  recognized,  and  its  manipulation  is  mastered,  yet  in  its  present  form 

it  is  doubtful  if  it  will  soon,  if  ever,  entirely  supersede  cement,  or  if  it 

offers  the  same  opportunities  for  permanency. 

The  advantage  ofifered  by  this  form  of  mount- 

Hdvantagcs.  ing  lies  mainly  in  the  comparative  ease  with  which 

the    bridge    may    be    subsequently    removed    in    the 

event  of  necessity,  anrl   without  injury  to  the  abutments,  supplemented 

by   the  relief   afforded   to   the   porcelain   part  on   account   of   the   more 


435 

cushion-like  effect  obtained  because  of  its  possible  elasticity  as  compared 
with  cement,  and  by  the  absence  of  any  cause  for  irritation  since  no 
surplus,  outside  of  the  actual  requirements,  need  obtain. 

In  the  application  of  gutta-percha  as  a  mount- 
Hpplication.  ing  medium,  the   ordinary  pink  base-plate  material 

seems  to  offer  the  greatest  opportunity  for  per- 
manency, because  of  its  inherent  toughness  and  durability.  In  its  use 
it  should  be  cut  into  small  narrow  strips  for  dowel  crowns,  and  small 
square  pieces  for  telescope  crowns,  and  as  it  can  only  be  manipulated 
at  a  temperature  which  will  admit  of  ready  and  accurate   adjustment, 


these  should  then  be  placed  on  a  smooth  surface  of  hot  iron,  or  of  some 
heating  device  which  avoids  contact  with  the  flame,  until  the  greatest 
possible  plasticity  is  obtained.  Fig.  338  illustrates  a  heating  device 
designed  for  this  purpose  by  Dr.  Geo.  Evans,  and  a  simple,  neat  and  in- 
expensive little  electric  heater  has  been  devised  by  Dr.  A.  H.  Wallace, 
of  San  Francisco. 

When  the  piece  involves  a  dowel  crown,  if  the  dowel  is  smooth  its 
sides  should  first  be  serrated  or  roughened  with  a  sharp  cutting  instru- 
ment, and  then  moistened  with  oil  of  cajaput,  or  eucalyptus,  as  a  means 
of  obtaining  attachment  thereto,  and  one  of  the  plastic  strips  then  coiled 
around  it  and  molded  to  closely  follow  its  form  with  the  fingers.  The 
bridge  should  now  be  placed  upon  the  heating  device  and  allowed  to 
remain  until  this  is  again  plastic,  when,  after  moistening  the  canal 
with  water  from  a  small  syringe,  or  some  essential  oil,  to  prevent  the 
gutta-percha  from  adhering  thereto,  the  bridge  should  be  forced  to  place. 

This  procedure  should  be  repeated  until  enough  of  the  material 
to  completely  fill  all  of  the  space  between  the  crown  or  abutment  piece 
and  the  root  has  been  added,  and  no  surplus,  beyond  this,  remains,  and 


436 

the  same  procedure  should  then  be  repeated  for  the  telescope  crowns 
excepting  that  in  this  type  of  crown  the  small  square  pieces  are  used 
instead  of  the  strips,  and  these  are  placed  in  the  cusps  and  around  the 
band,  the  surfaces  of  which  should  previously  be  roughened  or  serrated 
with  a  sharp  instrument. 

\Mien  a  sufficient  quantity  of  gutta-percha  has  thus  been  moulded 
into  each  abutment  piece  separately,  the  bridge  should  again  be  placed 
on  the  heater,  and  the  abutments  then  dried  with .  alcohol,  and  subse- 
quently moistened  with  a  thin  solution  of  gutta-percha  in  cajaput  or 
eucalyptus,  when  the  piece  may  then  be  finally  forced  to  place. 

This  solution  is  used  as  a  means  of  facilitating  a  more  secure  attach- 
ment of  the  gutta-percha  to  the  roots,  and  may  be  easily  made  b)'  first 
.  dissolving  the  material  in  chloroform — which  is  a  more  ready  solvent — 
and  then  gradually  adding  the  cajaput  or  eucalyptus  as  the  chloroform 
becomes  evaporated  until  a  stable  solution  of  the  proper  consistency 
obtains. 

Because  of  the  refractory  properties  of  base-plate  gutta-percha,  and 
in  order  to  overcome  this,  and  thus  simplify  the  manipulation,  various 
so-called  "gutta-percha  cements"  are  now  manufactured  and  more  or  less 
extensively  used,  and  the  outfit  of  this  kind  suggested  by  Dr.  Geo.  Evans 
is  very  complete.  Although  such  preparations  may  be  found  useful, 
still  the  increased  plasticity  and  a  possible  shrinkage,  together  with  the 
influence  of  normal  temperature,  makes  the  permanency  questionable, 
and  therefore,  since  it  is  these  same  refractory  properties  which  enhance 
the  value,  and  insure  the  maximum  durability  of  gutta-percha  as  a 
mounting  medium,  the  best  and  most  permanent  results  are  doubtless  to 
be  obtained  from  its  use  in  the  manner  indicated. 

Repairing. 

So  long  as  porcelain  facings  are  employed,  faulty  occlusions  are 
allowed  to  exist  and  remain  faulty;  for  purely  economical  or  other  rea- 
sons the  requirements  uf  strength  are  not  religiously  observed,  and 
patients  are  not  cautioned  to,  and  do  not  exercise  moderate  care,  the 
occasional  repair  of  fixed  bridgework  will  become  to  be  a  necessity.  For 
these  reasons  it  is  evident  that  the  operator  must  possess  a  knowledge 
of  the  procedures  incident  to  effecting  repair  in  the  best  and  most  ex- 
pedient manner. 

Perha]js  llic  mcjst  common  accident  which  hap- 
Tracturcd  facings,      pens  to  fixed  bridgework  is  the   fracturing  of  por- 
celain   facings,  but   unless  this  is  accompanied   with 
other   complications   which   demand   the   rcnujval   of   tlic   i)iecc,   the   pro- 


437 

cedure  is  usually  comparatively  simple  and  easy,  and,  as  applied  to 
bridgework,  is  identical  with  that  incident  to  the  replacement  of  single 
facings  as  previously  considered  at  some  length  in  connection  with 
crown  work.     (See  page  176.) 

While  one  or  even  two  facings  may  be  replaced  by  any  of  these 
previously  mentioned  methods,  still,  when  the  replacement  of  more  than 
two  on  the  same  piece  is  demanded,  it  is  usually  best  to  remove  the 
bridge,  obtain  models,  and  attach  the  new  ones  by  backing  them  up  and 
soldering. 

When  the   removal  of  the  bridge  is  demanded 
Removing  as  a  means  of  affording  opportunity  for  thus  attach- 

and  Soldering.         ing  new  facings,  or  for  eft'ecting  repair  of  the  metal 
parts  by  soldering,  the  greatest  care  must  be  exer- 
cised to  avoid  inflicting  unnecessary  pain  upon  the  patient,  and  to  preclude 
the  possibilities  of  doing  injury  to  the  supporting  roots. 

For  this  reason  it  is  necessary  to  first  break  or  destroy  the  fixity 
of  the  attachment  of  the  abutment  pieces.  In  this  connection  the  shell  or 
telescope  crowns  should  first  be  loosened,  and  if  it  be  desirable  to  pre- 
serve the  continuity  of  the  band  in  order  to  admit  of  subsequently  re- 
placing the  crown,  this  may  best  be  accomplished  by  means  of  drilling 
a  small  hole  under  the  cusps,  and  lifting  it  upward  or  downward  with 
a  heavy  pointed  instrument  as  previously  described  in  connection  with 
Fig.  114,  until  it  is  loosened.  If  the  crown  is  not  to  be  used  again  the 
crown-slitting  forceps,  if  preferable,  may  be  used  for  this  purpose. 
The  dowel  crowns  should  then  be  likewnse  loosened  in  their  attachment, 
but  unless  this  may  be  accomplished  by  the  degree  of  mobility  afforded 
by  the  loosening  of  the  other  end,  and  by  the  gradual  working  of  the 
piece,  the  procedure  is  considerably  more  difficult,  and  may  require  that 
the  dowel  crowns  be  first  separated  from  the  remainder  of  the  bridge, 
which  may  be  done  with  a  thin  edg.-  carborundum  stone ;  or  else  that  the 
dowel  be  separated  from  the  cap  by  means  of  a  small  stone  and  then  a 
bur,  used  in  the  engine,  as  also  previously  described  in  connection  with 
crown  work.     (See  page  184.) 

As  soon  as  all  of  the  abutment  pieces  are  thus  loosened  the  piece  may 
be  detached  and  all  remaining  cement  then  removed  with  a  suitable  bur, 
after  which  it  should  be  subjected  to  the  acid  bath  and  allowed  to  re- 
main therein  until  perfectly  clean. 

If  much  mutilation  of  the  crowns  has  resulted  they  should  be  sepa- 
rated from  the  piece  with  a  fine  mechanical  saw.  and  then  repaired,  or 
replaced  by  new  ones.  After  repairing  the  old  ones,  or  constructing  new 
ones,  they  should  be  adjusted  to  place  on  the  abutments  and  an  impres- 


438 

sion  and  model  obtained,  after  which  the  remaining  parts  may  be  as- 
sembled on  the  model  and  the  case  invested  and  soldered. 

Where  broken  facings  are  to  be  replaced  by  new  ones,  the  old  back- 
mgs  should  be  sawed  out,  and  the  remaining  parts  placed  in  position  in 
me  mouth  and  an  impression  and  model  obtained,  when  the  new  facings 
may  be  selected,  ground  to  fit,  backed  up,  and  the  case  then  also  invested 
and  soldered. 

•  In  order  to  facilitate  the  repairing  of  bridges  which  have  been 
worn,  by  means  of  soldering,  however,  it  is  always  necessary  to  observe 
that  absolute  cleanliness  of  the  parts  has  been  effected. 


Porcelain  BriageworR. 


CHAPTER    XXV. 

Indications.      Requirements.      Application    and    Construction :    Anterior    Bridges, 

Posterior  Bridges,  Dowel  Crowns  as  Abutment  Pieces.     All  Porcelain 

Dummies :  Making  Porcelain  Blocks,  Building, 

Carving  and  Baking,  Repairing. 


The  application  of  porcelain  to  the  construction  of  bridgework  may 
be  recorded  as  being  among  the  early  achievements  of  modern  dental 
ceramics,  and  while  still  perhaps  in  a  more  or  less  uncertain  stage  of 
development,  it  has  nevertheless  always  been  regarded  by  those  who 
recognized  its  cosmetic  and  hygienic  possibilities,  as  the  ideal  type  of 
prosthesis. 

Unfortunately,  however,  an  early  wave  of  enthusiasm  following  its 
introduction  by  Land,  Parmley  Brown  and  others,  led  to  such  general 
and  indiscriminate  use  as  to  bring  grief  and  discouragement  to  those  who 
became  overzealous,  and  who,  while  quick  to  appreciate  its  possibilities, 
were  equally  slow  in  recognizing  its  limitations. 

As  a  result,  a  very  large  proportion  of  the  primitive  efforts  in  this 
direction  were  such  signal  failures  as  to  dishearten  even  the  most  san- 
guine, and  the  progress  and  development  which  had  previously  seemed 
so  desirable  and  so  certain  was  thereby  materially  retarded. 

For  the  reason  that  purely  cosmetic  and  hygienic  "possibilities," 
however,  do  not  encompass  the  entire  range  of  the  requirements  of  dental 
bridgework,  such  a  result  was  but  a  natural  sequence  essential  to  the 
experimental  stages,  and,  since  it  is  largely  by  our  failures  that  we  learn, 
this  era  of  disaster  and  discouragement  was  b}''  no  means  unproductive, 
for  it  served  to  develop  the  faculty  of  reasoning,  and  the  power  of 
discrimination  to  an  extent  which  awakened  recognition  of  the  fact  that 
porcelain  has  its  limitations. 


440 

If  it  is  conceded  that  all  of  the  combined  requirements  in  the  com- 
posite— and  to  the  highest  possible  degree,  must  obtain  in  any  class  of 
work  destined  to  be  permanently  successful ;  that  porcelain  is  a  vitrious 
and  friable  substance,  by  no  means  indestructible,  and  that  inherent 
strength  is  one  of  the  prerequisites  of  bridge  construction — all  of  which 
are  indisputable — it  is  then  evident  that  porcelain  work  is  not  universally 
applicable,  and  that  when  it  is  chosen  a  degree  of  strength  com- 
mensurate with  the  requirements  must  obtain. 

On  the  other  hand,  and  irrespective  of  these  facts,  its  application 
embraces  so  great  a  field  of  usefulness  as  to  insure  its  permanency  as 
an  art,  and  this  field,  circumscribed  though  it  may  be,  will  increase  in 
proportion  as  the  aim  for  higher  artistic  attainment  is  cultivated  and 
developed,  and  in  proportion  as  a  more  definite  knowledge  of  the  limita- 
tions may  be  recognized,  and  the  actual  requirements  observed. 

Success  or  failure  will  therefore  depend  largely  upon  two  factors ; 
first,  upon  judicious  application,  and  second,  upon  an  observation  of  such 
details  of  technique  as  are  essential  to  insuring  a  nL;ximum  degree  of 
strength  in  the  finished  piece. 

In  order  that  the  application  may  be  judicious,  however,  it  is  obvious 
that  the  conditions  must  be  favorable,  and  when  they  are  not,  or  may  not 
be  made  so,  porcelain  can  not  be  a  conservative  reliance  and  is  therefore 
contraindicated. 

Tndications. 

In  studying  the  conditions  which  are  favorable  to  the  application  of 
porcelain  bridgework,  the  inherent  physical  characteristics  of  this  vitrious, 
friable  substance  must  be  recognized,  and  whilst  it  is  capable  of  with- 
standing stress  to  a  degree,  the  stress  to  which  it  may  safely  be  sub- 
jected will  increase  in  proportion  as  its  thickness  or  "bulk"  may  increase, 
and  will  decrease  correspondingly. 

It  is  therefore  evident  that  the  application  of  porcelain  bridges  is 
indicated  only  in  such  cases  as  present  an  extent  of  absorption  and  an 
occlusion  which  are  favorable,  or,  in  other  words,  a  condition  where 
ample  space  exists,  for  only  under  such  circumstances  may  opportunity 
be  afforded  for  the  use  of  sufficient  bulk  to  prove  adequate  to  the  demands 
for  integral  strength. 

As  the   extent   of  absorption   increases   in  pro- 
Removable  Bridges,     portion  to  the  length  of  time  elapsing  since  the  loss 
of  the  natural  teeth,  together  with  the  number  which 
are  missing ;  and  as  the  application  of  "fixed"  bridges  to  very  extensive 
cases  is  rarely  indicated,  it  is  apparent  that  porcelain  bridgework  is  more 


441 

generally  applicable  to  removable  structures  where  ample  space,  support 
and  protection  is  afforded,  than  to  bridges  which  are  designed  to  be 
permanently  attached  to  the  supporting  teeth,  and  when  the  application 
is  confined  to  this  class  of  construction  the  very  highest  type  of  cosmetic, 
hygienic  and  serviceable  prosthesis  may  be  obtained. 

Under  the  same  or  similar  conditions  the  ap- 
TlX^d  Bridges.  plication  to  "fixed"  bridges,  to  which  this  chapter 
will  be  entirely  devoted,  may  also  be  equally  prac- 
ticable, and  offer  the  same  advantageous  features.  In  this  connection, 
however,  every  opportunity  for  observing  all  of  the  combined  require- 
ments must  present,  and  even  then  the  most  successful  results  will  obtain 
by  confining  the  application  to  smaller  and  less  extensive  bridges,  or  to 
parts  of  bridges  in  combination  with  gold. 

Hcquirements. 

Coincident  with  favorable  indications  the  fundamental  requirements 
of  successful  application  demand  a  degree  of  judgment  equally  sound, 
and  a  degree  of  knowledge  equally  broad,  and  these  must  then  be  sup- 
plemented by  a  particularly  painstaking  observation  of  details.  Indeed, 
in  perhaps  no  other  one  class  of  mechanical  procedure  must  every  part 
of  the  technique  be  so  carefully  observed  as  in  porcelain  work,  and  a 
recognition  and  appreciation  of  this  fact  at  the  very  outset,  will  form 
an  impregnable  fortification  to  the  stronghold  of  ultimate  success,  for  all 
whose  ambition  leads  them  in  this  direction. 

Regardless  of  the  previously  mentioned  more  or  less  unfavorable 
characteristics  of  porcelain,  a  far  greater  number  of  failures  in  this  type 
of  bridgework  can  be  attributed  to  an  inadequate  degree  of  knowledge, 
or  to  an  indifferent  observation  of  the  details  in  connection  with  the 
requirements,  than  can  ever  be  traced  directly  to  the  faults  of  porcelain 
itself.  In  fact  almost  any  of  the  various  makes  and  grades  of  porcelain 
compounds  possesses  the  necessary  strength  and  may  be  successfully 
used  provided  the  proper  attention  be  given  to  the  construction  of  the 
metal  parts  which  are  to  form  the  substructure,  before  the  "body"  is 
added  thereto. 

Therefore,  while  it  is  true  that  much  also  depends  upon  the  character 
of  the  porcelain  selected,  and  still  more  upon  its  proper  manipulation, 
yet  since  it  is  at  best  but  a  friable  substance,  and  since  little  or  no  physical 
union  obtains  between  it  and  the  supporting  structure,  it  is  evident  that 
the  practicability  of  this  class  of  work  will  always  depend  largely  upon 
the  support  and  protection  afforded  to  the  porcelain  by  the  substructure. 


442 

For  these  reasons  the  substructure  must  neces- 
SubStructUK.  sarily  be  constructed  in  such  manner  as  to  afford  a 

strong,  unyielding,  ivell-adapted  base  which  will, 
first,  mechanically  sustain  and  support  the  porcelain  part  of  the  piece; 
and  second,  which  will  protect  this  porcelain  against  cleavage,  and  from 
the  influences  of  stress,  in  all  directions. 

While  the  employment  of  platinum  is  of  course  necessary  as  a  means 
of  insuring  a  degree  of  infusibility  which  will  withstand  the  temperature 
required  to  fuse  any  of  the  porcelain  compounds  used  for  this  pur- 
pose, the  requirements  of  strength  not  infrequently  indicate  the  \xs,e  of 
iridio-platinum;  and  all  of  the  various  parts  must  then  be  assembled 
in  a  manner  which  will  preclude  the  possibility  of  any  subsequent  change 
in  their  relation  as  a  result  of  the  shrinkage  of  the  "body"  in  fusing. 

The  assemblage  of  the  various  parts  of  a  bridge 
Pure  Gold  ?$  a  SoWer.  with  p\ire  gold  as  i^  solder,  which  was  the  former 
and  is  the  common  practice,  has  proven  to  be  entirely 
inadequate  to  these  combined  requirements,  when  any  of  the  higher 
fusing  "bodies"  are  used.  This  is  due  to  the  fact  that  its  absorption  by 
the  platinum  at  its  melting  point,  or  its  volatilization  at  a  higher  tempera- 
ture, or  both,  to  which  gold  is  susceptible  in  the  furnace,  absolutely  pre- 
cludes the  making  of  strong  joints,  or  of  any  reinforcement,  and  for  this 
reason  does  not  prevent  a  change  of  form  as  a  result  of  the  shrinkage. 

Such  a  possibility  may  be  entirely  overcome, 
Platinum  Solder.  however,  and  adequate  strength  insured  by  using 
25  per  cent,  platinum  solder  throughout  the  con- 
struction of  the  entire  substructure,  and  including  the  attachment  of 
the  facings.  As  this  alloy  is  ordinarily  not  disturbed  in  the  fusing  of  the 
"body,"  a  secure,  strongly  reinforced  and  reliable  assemblage  may  thereby 
be  effected,  for  which  reason  its  use  is  universally  recommended. 

As  a  further  means  of  insuring  and  providing 

Prowldinfl  ^°^  strength,  the  adjustment  of  the  parts  constitut- 

for  Strengtb  of         ing  the  substructure  must  be  made  in  such  manner 

Porcelain.  as  to  avoid  unnecessarily  diminishing  the  strength  of 

the  porcelain  to  be  subsequently  applied.     This  may 

be  accomplished  by  keeping  all  of  the  metal  parts  in  such  close  proximity 

with  each  other  as  to  preclude  dividing  the  mass  of  porcelain  through  its 

center,  or  into  small  sections,  which  is  always  an  element  of  weakness 

and  must  be  avoided. 

If  the  requirements   of  the   metal    substructure 

Porcelain  €omS)OUndS.   -'ire  thus  observed  it  is  evident  that  but  little  strength 

in  the  porcelain  itself  will  be  actually  required,  and 


443 

hence,  as  previously  stated,  various  grades  of  these  compounds  may  be 
successfully  employed  if  properly  manipulated. 

Owing  to  the  excessive  shrinkage  of  the  so-called  "low"  fusing 
bodies,  however,  as  compared  with  the  less  fusible  compounds,  the  re- 
quirements of  bridgework,  where  so  large  a  quantity  is  to  be  used  in 
obtaining  contour,  and  where  stability  of  form  and  color  are  so  essential, 
will  be  best  conserved  by  the  employment  of  those  classified  as  "high" 
fusing. 

This  is  manifest  for  the  reason  that  a  minimum  of  shrinkage,  com- 
bined with  a  maximum  degree  of  stability  of  form  and  color,  must  neces- 
sarily facilitate  and  expedite  the  procedure.  And  those  readily  apparent 
advantages  may  also  be  still  further  increased  by  using  one  grade  of 
"body"  throughout  the  construction  of  the  piece,  instead  of  beginning 
with  the  so-called  "foundation"  and  finishing  with  "enamel,"  for  the  rea- 
son that  in  the  use  of  one  grade,  a  more  uniform  shrinkage  will  prevail, 
and  therefore  if  the  piece  is  built  up  to  the  desired  form  and  contour  for 
the  first  bake,  tzvo  fusings  will  usually  be  sufficient  to  complete  the  case, 
while  in  the  use  of  two  grades  the  uneven  shrinkage  will  usually  require 
three,  or  more,  to  produce  the  same  finished  result. 

JTpplication  and  Construction. 

While  all  of  the  fundamental  principles  and  requirements  incident  to 
the  application  and  construction  of  fixed  bridgework  in  general  apply 
also,  and  with  equal  emphasis,  to  porcelain  work  in  particular,  yet,  in 
addition  thereto  it  must  also  be  remembered  that  the  details  of  construc- 
tion should  be  even  more  closely  observed,  and  more  carefully  executed. 

If  these  considerations  are  recognized  as  being  essential  to  success, 
and  the  application  is  made  in  accordance  therewith,  the  scope  of  prac- 
ticability, and  of  cosmetic  possibilities,  will  be  limited  onl\-  In-  the  capa- 
bility of  the  operator  to  exercise  judgment  in  the  application,  and  to 
acquire  skill  in  the  details  of  construction. 

Anterior  Bridges. 

Since  the  cosmetic  requirements  are  of  course  confined  mainlv  to  that 
area  of  the  arch  which  is  within  the  range  of  vision,  it  is  evident  that  the 
greatest  demand  for  porcelain  bridgework  will  be  in  such  cases  as  in- 
volve the  replacement  of  any  of  the  ten  or  twelve  anterior  teeth,  but  as 
applied  particularly  to  all,  or  to  any  part  of,  the  six  anterior  teeth  fzvo 
general  types  of  construction  are  employed,  though  each  one  is  subject 
to  manv  variations. 


444 

These  differ  from  each  other  only  as  relates  to  the  use  of  a 
"saddle,"  and  while  the  best  results  in  porcelain  bridgework  are  usually 
to  be  obtained  by  utilizing  this  principle,  there  are  cases  where  the  extent 
of  absorption  which  has  taken  place  would  not  indicate,  nor  admit  of,  the 
use  of  a  saddle,  and  where  the  more  simple  form  of  construction  would 
thus  become  necessary.  It  must  be  remembered,  however,  that  even 
though  a  saddle  may  not  be  indicated  there  must,  nevertheless,  be  room 
enough  for  a  strong  mass  of  porcelain  or  this  type  of  bridge  construction 
is  contraindicated. 

In  either  of  the  above-mentioned  general  types 
m^tbOdS  the  methods  of  attachment  to  the   supporting  teeth 

of  flttacbmcnt,  must,  as  usual,  be  first  determined,  and  their  adapta- 
tion then  effected. 
While  inlays  made  of  25  per  cent  platinum  solder  and  applied  in 
accordance  with  the  requirements  previously  mentioned,  or,  some  of  the 
various  other  forms  of  attachment — also  made  with  platinum  solder — 
may  sometimes  be  used  to  advantage  still  the  possibilities  for  reproducing 
the  natural  crowns,  together  with  the  additional  strength  and  greater 
permanency  afforded  by  the  use  of  artificial  crowns,  will  usually  indicate 
the  more  or  less  general  choice  of  the  latter  as  "attachments"  or 
"abutment  pieces." 

When    crowns    are    used    the    roots    should    be 
POfCdaln  0rown$.      prepared  as  usual,  and  the  platinum  cap,  including 
the    dowel,    completed    as    previously    indicated    for 
single  porcelain  crowns. 

Because  of  the  additional  requirements  of  strength  incident  to  bridge 
construction,  however,  the  band — if  one  is  used — should  be  at  least  28  g., 
and  the  floor  in  either  instance  should  not  be  thinner  than  32  g.,  and 
while  the  union  of  the  band,  the  floor  and  the  dowel  may  be  made  with 
pure  gold — without  precluding  the  subsequent  use  of  platinum  solder  in 
the  final  assemblage  of  the  piece — if  absolute  contact  exists — neverthe- 
less, the  safest  results  will  usually  obtain  from  the  use  of  platinum  solder 
for  this  purpose  also ;  and  where  a  band  is  used  the  joint  should  invariably 
be  lapped  in  either  event,  as  a  means  of  precluding  the  possibility  of  its 
opening  in  the  furnace,  as  well  as  of  insuring  a  maximum  degree  of 
strength. 

Cvpical  Construction* 

In  the  construction  of  small,  simple  bridges  in  the  anterior  part  of  the 
mouth  the  use  of  a  saddle  beneath  tlie  dummies  is  rarely  indicated  unless 
demanded  by  excessive  absorption  and  as  a  support  for  porcelain  for 
gum  restoration. 


445 

When  a  saddle  is  for  this  reason  unnecessary, 

UlithOUt  Saddle.        or  contraindicated,  the  caps,  or  other  abutment  pieces, 

should  first  be  completed  and  then  placed  in  position 

upon  the  roots  or  supporting  teeth,  properly  adjusted  in  their  relation 

thereto,  and  the  final  "bite"  and  impression  taken. 

As  the  preservation  of  the  model  throughout  the  construction  of 
porcelain  bridges  is  quite  essential,  the  interior  of  the  caps  when  removed 
in  the  impression  should  always  be  filled  with  wax  as  a  means  of  facilitat- 
ing their  subsequent  removal  and  accurate  replacement  when  the  model  is 
obtained,  and  this  feature  should  be  observed  irrespective  of  the  style  of 
abutment  piece  employed. 

After  obtaining  the  model,  adjusting  the  bite,  and  mounting  upon  the 
articulator,  suitable  facings  should  then  be  selected,  and  ground  to  fit 
the  caps  and  the  intervening  model,  and  to  the  proper  relation  with  each 


f=iq.  339. 

other.  In  this  connection  at  least  two  precautions  are  necessary.  First, 
the  facings  which  are  to  be  adapted  to  the  caps  must  be  ground  thin 
enough  to  overlap  upon  the  labial  surface  of  the  bands,  for  the  reason 
previously  mentioned  (Fig.  339)  ;  and  second,  some  little  space  should 
always  exist  between  the  facings  in  order  to  admit  of  their  expansion 
during  the  process  of  soldering. 

When  the  desired  adjustment  has  been  obtained  the  caps  should  be 
slightly  warmed  and  detached  from  the  model  and  then  held  in  the  flame 
until  the  wax  is  removed  from  them.  After  observing  that  they  then  go 
readily  to  place,  and  that  they  may  also  be  easily  removed,  they  should 
be  adjusted  to  position  and  the  surface  of  the  model  between  them  cov- 
ered with  tin  foil.  (Fig.  340.)  The  facings  should  now  be  properly  ad- 
justed and  securely  attached  with  hard  wax,  after  which  the  entire  piece 
may  be  easily  removed  from  the  model  (owing  to  the  presence  of  the 
tin  foil)  and  invested. 

Except  that  the  entire  lingual  surface  of  all  of 
Tnv>C$tin9.  the    facings   must   be    freely   exposed,  and   that   the 

investment  must   have  body   enough   to  hold   it  to- 
gether and  to  withstand  the  stress  necessary  to  properly  adjust  the  pins 


446 

to  the  connecting  bar,  the  requirements  incident  to  investing  porcelain 
bridges  do  not  differ  essentially  from  those  in  general,  but  these  precau- 
tions must  be  observed. 


When  thus  invested  the  wax  should  be  carefully  removed  and  all 
!hin  overhanging  edges  then  trimmed  away  until  the  facings  are  freely 
exposed.     (Fig.  341.) 


Ficj.  341. 


A  connecting  bar  of  round  iridio-platinum  wire 
Connecting  Bar.  not  smaller  than  16  g.  should  now  be  adjusted,  and 
as  the  strength  of  the  finished  bridge  will  depend 
largely  upon  this,  it  is  therefore  evident  that  an  adjustment  such  as  will 
insure  strength  must  obtain.  In  effecting  this  the  bar  should  first  be  bent 
so  as  to  approximately  follow  the  curvature  of  the  facings,  and  then 
cut  the  proper  length.  The  ends  should  now  be  flattened  on  the  anvil 
and  trimmed  so  as  to  rest  firmly  on  each  cap,  up  close  to  the  facings,  both 
of  which  provisions  arc  for  the  purpose  of  obtaining  strength  without 
materially   weakening   the    porcelain.      (Fig.    342.) 


447 

Ordinarily,  however,  where  a  saddle  is  not  used,  this  bar  should  not 
come  in  direct  contact  with  the  intermediate  facings,  or  dummies,  but 
should  be  so  adjusted  as  to  admit  of  bending  the  pins  down  until  their 
ends  come  in  contact  with  the  bar,  and  yet  leave  some  little  space  between 
it  and  the  facing.  (Fig.  343.)  This  is  desirable  for  the  reason  that 
where  no  saddle  is  used  it  is  seldom  if  ever  advisable  to  attempt  to  com- 
pletely cover  the  bar  with  porcelain,  as  it  would  be  likely  to  chip  off 


/yy.  342. 

afterward,  and  that  if  some  little  space  exists  opportunity  for  effecting 
the  necessary  contour  and  for  obtaining  the  necessary  strength  in  the 
finished  piece  without  completely  covering  the  bar,  is  thus  afforded. 


F/q.  343. 


When  the  bar  has  been  so  adjusted,  each  pin  of  each  facing  should 
then  be  bent,  usually  downward,  or  toward  the  cervical,  until  absolute 
contact  with  the  bar  is  obtained.  This  may  be  accomplished  by  securely 
holding  the  facing  against  the  investment  w'ith  a  blunt  instrument  in 
one  hand,  while  the  pin  is  bent  with  a  sharp  instrument  in  the  other, 
being  careful  always  to  apply  the  pressure  to  the  extreme  end  of  the  pin 
and  to  hold  the  facing  securely. 

If  absolute  contact  is  impossible  a  small  piece  of  platinum  plate  or 
wire  should  now  be  fitted  into  the  space,  as  a  means  of  facilitating  the 
subsequent  union  with  solder,  and  if  the  bar  is  not  inclined  to  remain  in 
place  and  preserve  the  contact  thus  obtained  small  pieces  of  investment 


448 

material  or  fire-clay  should  be  fitted  so  as  to  support  it  and  thus  insure 
a  preservation  of  the  contact  when  the  case  is  heated  for  soldering. 

When  all  of  these  requirements  have  been  carefully  observed  the  case 
should  then  be  placed  upon  the  flame  and  allowed  to  remain  until  thor- 
oughly heated,  after  which  the  parts  should  be  united  with  25  per  cent 
platinum  solder,  being  careful  to  observe  that  every  pin  is  securely  at- 
tached to  the  bar,  and  that  the  ends  of  the  bar  are  then  also  securely 
attached  to  the  caps.  The  completed  substructure  for  this  type  of  bridge 
is  illustrated  in  Fig.  344. 

This  same  general  type  of  construction  would  also  be  equally  ap- 
plicable to  the  support  of  the  four  incisors  by  the  two  cuspids,  or,  in 
favorable  cases,  may  even  be  further  extended  on  one  or  both  sides  so 
as  to  involve  the  bicuspids,  but,  in  this  latter  connection  it  is  well  to  re- 
member that  the  practicability  of  porcelain  bridgework  diminishes  as  the 
size  of  the  piece  increases,  and  that  small  bridges  will  therefore  be  more 


Ficj.  344. 

successful  than   large   ones,   unless  the  latter  are   made   in   combination 
with  gold. 

Other  typical   styles  of  construction  where  no  saddle  is  employed, 
and  which  are  more  or  less  practicable,  are  illustrated  in  Fig.  345. 

In  such  cases  as  demand  the   use  of  a  saddle 

UPitb  Saddle.  because  of  the  necessity  for  gum  restoration  due  to 

excessive  absorption,  the  application  must  be  made 

in  accordance  with  all  of  the  various  requirements  previously  considered 

in    connection   with    "saddle   bridges,"    in    conjunction    also    with    those 

essential  to  porcelain  work. 

This  type  of  construction  in  a  typical  case  which  involves  the  cardinal 
principles  is  illustrated  in  Fig.  346. 

Posterior  Briagcs. 

Notwithstanding  the   apparent   objections   to  the   saddle   in   "fixed" 
bridgework,  and  the  tendency  to  avoid  its  use  whenever  and  wherever 


449 


Fiq.  345. 


Fiq.  3^6. 


450 

possible,  it  must  nevertheless  be  remembered  that  where  the  porcelain 
part  of  the  structure  is  to  be  subjected  to  masticatory  stress,  some  means 
of  protecting  and  supporting  it  viiist  always  be  provided. 

Failure  to  properly  appreciate  and  observe  thi^ 

mitbOUt  Saddk.         requirement  only  means  failure  in  the  application  of 

porcelain  bridges  to  the  posterior  teeth.    The  type  of 

construction    which   was   used    prior   to   a   recognition    of   this    fact,    but 


r/(^.  347. 

which  has  been  abandoned  because  of  the  proportion  of  failures  which 
invariably  presented,  and  in  which  the  entire  occlusal  surfaces  of  porce- 
lain became  fractured  and  broken  away  by  the  stress  of  mastication,  as  a 
direct  result  of  being  inadequately  supported  and  protected,  is  illustrated 
in  Fig.  347. 

Cvpical  Construction. 

For  this  reason  it  is  apparent  that  if  porcelain  bridgework  is  to  be 
used  in  replacing  posterior  teeth,  the  use  of  the  saddle  is  invariably 
essential  to  its  successful  application,  and  as  applied  to  posterior  bridges, 
about  the  only  exception  to  the  rule  is  in  those  simple  and  quite  common 
cases  where  the  second  bicuspid  is  used  to  support  the  missing  first 
bicuspid,  and  where  the  presence  of  cusps  upon  the  tooth  thus  suspended 
is  usually  unnecessary.  The  type  of  construction  which  may  generally  be 
used  with  success  in  this  particular  class  of  cases  is  illustrated  in 
Fig.  348,  but  in  the  baking  of  such  cases  no  effort  should  be  made  to 
entirely  cover  the  projecting  end  of  the  connecting  bar  which  supports 
the  dummy,  with  porcelain,  for  it  would  be  certain  to  chip  or  creak  away 
unless  made  unusually  and  objectionably  clumsy. 

While   the   details   incident   to   the   construction 
mitb  Saddle.  of  posterior  bridges  in  porcelain  are,  of  course,  sub- 

ject to  many  modifications  and  variations,  the  saddle 
is  thus  essential,  and  the  underlying  principles  are  practically  invariable, 
and  may  be  elucidated  in  a  general  way  by  the  presentation  of  typical  cases. 

As  mentioned  in  connection  with  the  construction 

methods  of  anterior  bridges,  while  inlays  made  of  twenty-five 

Of  flttacbment.  per  cent,  platinum  solder,  or  any  of  the  various  other 

forms  of  attachment  to  the  supporting  teeth  which, 


451 

when  also  likewise  made,  may  seem  to  offer  opportunity  for  obtaining 
permanency,  and  may  therefore  be  sometimes  used,  the  best  results, 
particularly  in  posterior  bridges  where  the  stress  is  greater,  will  usually 
obtain  from  the  use  of  either  dowel  or  telescope  crowns  as  the  abutment 
pieces,  for  the  reason  that  the  durability  of  the  piece  is  thereby  increased. 

When   porcelain   dowel   crowns   are   to   be  used 

Dowel  Crowns.  on  one,   or  both,  ends  the  caps  with  or  wathout  a 

band,  as  may  be  preferred,  should  first  be  made  and 

fitted  in  the  manner  indicated.     When  completed  these  should  be  placed 

in  position  on  the  roots  and  a  plaster  impression  taken,  from  which  the 

die  and  subsequently  the  counter  die  may  be  made.     (See  Fig.  299.) 


yiiiiiiiiiiiiiiiiiiiiiiiiiiiiiij! 

The  saddle  should  now  be  swaged  of  30  to  32  gauge  platinum, 
trimmed  to  the  proper  outline,  fitted  in  the  mouth  with  the  caps  in  place, 
and  then  soldered  thereto  with  platinum  solder  as  indicated  in  ^'saddle 
bridges"  in  the  preceding  chapter. 

When  the  metal  framework  is  thus  completed  it  should  be  placed  in 
the  mouth  and  the  edges  of  the  saddle  burnished  to  a  close  adaptation  to 
the  tissue  upon  which  it  rests,  after  whicli  the  "bite"  and  impression 
should  be  taken. 

The  interior  of  the  caps  should  now  be  filled  with  melted  wax — in 
order  to  admit  of  their  removal  from  the  model — -and  the  model  should 


452 

then   be   made,   the   wax   "bite"   properly   adjusted   to   it,   and   the   case 
mounted  upon  the  articulator. 

While  the  entire  porcelain  part  of  the  bridge  may 
UlitbOUt  facings.  be  built  up  with  "body,"  and  suitably  and  more  or 
less  artistically  carved,  after  making  provision  for 
its  mechanical  support  by  and  retention  to  the  base  or  substructure,  the 
use  of  facings  is  universally  recommended.  Indeed,  as  a  means  of  ob- 
taining proper  form  and  color,  their  use,  wherever  possible,  is  essential 
to  the  achievement  of  the  most  artistic  results. 

When    suitable     facings    have    therefore    been 

Ulitl)  facings.  properly  selected  and  are  then  ground  to  the  required 

adjustment,  they  should  be  temporarily  but  securely 

assembled  with  hard  wax,  and  the  entire  piece  removed  from  the  model 

and  invested  in  accordance  with  the  requirements. 

The  connecting  bar,  which  should  be  of  round 

Connecting  Bar.  iridio-platinum   wire   from    14   to    16   gauge,   should 

now  be  fitted  under  the  pins  and  as  close  to  the  saddle 

and  facings  as  possible,  with  each  end  resting  firmly  upon  the  caps,  and 


ficj.349. 

when  so  adjusted  each  pin  should  be  bent  down  until  in  direct  contact 
with  the  bar.  Where  such  contact  is  impossible  a  small  piece  of  wire  or 
plate  should  be  snugly  fitted  into  the  space  between  the  end  of  the  pin 
and  the  bar,  in  order  to  facilitate  soldering  and  to  insure  strength. 

Owing  to  the  difficulty  of  bending  iridio-platinum  wire  of  this  size 
to  conform  to  such  adaptation.  Dr.  W.  H.  Taggart  has  suggested  a  means 
of  facilitating  the  procedure  by  twisting  several  pieces  of  small  platinum 
wire,  such  as  is  used  in  electric  furnaces  (28  or  29  gauge),  into  a  "rope" 
of  suitable  size,  and  after  adjusting  this  to  the  requirements,  subsequently 
filling  it  in  with  platinum  solder  in  the  assemblage  of  the  parts.  This 
will  answer  llic  ]nu-]jose  nicely,  but  is  not  so  strong  as  a  drawn  wire. 

When   the    connecting   bar   has    been   thus    ad- 
Cingual  Support.         justed,   a  means   of   insuring  adequate   support  and 
protection  to  the  ])orcelain  which  is  to  form  the  masti- 
cating surfaces  should  then  be  provided. 

This  may  be  observed  to  the  best  advantage  by  fitting  small  strips 
or  28  gauge  platinum  jjlale  to  the  lingual  edge  of  the  saddle,  immediately 
back  of  each  facing,  as  also  recommended  in  the  construction  of  single 


453 


crowns.  These  may  be  bent  to  fit  more  or  less  closely  upon  the  saddle, 
and  when  soldered  thereto  will  form  a  lingual  outline  for  contouring  the 
porcelain,  and  a  cup-shaped  receptacle  for  its  support  and  protection. 
(Fig.  349.) 

To  facilitate  the  retention  of  these  separate  pieces  in  their  proper 
relation  to  the  saddle  while  soldering,  they  should  be  so  adapted  as  to 
allow  the  extreme  edge  of  the  saddle  to  project  slightly  beyond  them. 
This  forms  a  narrow  shoulder  upon  which  the  solder  may  be  placed,  and 
v/hen  the  assemblage  has  been  completed,  this  edge  may  be  finished 
down  to  a  flush  and  even  joint. 


Fjq.  350. 


The  width  of  this  lingual  extension  or  support  may  vary  from  1-16 
of  an  inch  to  a  distance  equal  to  half  the  length  of  the  facings  used,  or 
even  greater,  and  ma\-  furthermore  be  swaged  in  one  piece,  by  means  of 
an  impression  and  dies,  if  desired,  but  the  former  width  is  usually  all  that 
is  required,  and  a  better  conformation  to  the  form  of  the  saddle  can 
usually  be  obtained  by  using  separate  pieces  instead  of  attempting  to 
adapt  a  single  piece. 


454 

In  effecting  the  final  assemblage  sufiicient  solder  to  make  good  joints 
and  insure  adequate  strength  should  alwa3^s  be  used. 

This  type  of  construction,  which  is  applicable  to  short  bridges  in  the 
upper  jaw,  is  illustrated,  in  the  metal  and  in  the  finished  piece,  in  Fig.  350. 

Another  more  simple  application  involving  the  support  of  a  missing- 
second  bicuspid,  by  means  of  a  dowel  crown  upon  the  root  of  the  first 
bicuspid,  and  a  support  in  the  first  molar  is  illustrated  in  Fig.  351,  For 
the  reason  that  the  second  bicuspid  should  usually  be  provided  with  an 
occlusal  surface,  the  use  of  a  small  saddle  beneath  it  and  of  some 
form  of  support  on  the  posterior  end  is  therefore  made  necessary.  This 
support  may  be  obtained  by  allowing  the  projecting  end  of  vlic  connecting 
bar  to  simply  rest  snugly  in  a  gold  inlay  or  filling  previously  inserted 


Ficj.  352. 

and  grooved  for  its  accommodation — as  illustrated  and  mentioned  in  the 
chapter  on  "fixed  bridgework,"  or,  it  may  be  obtained  by  means  of  an 
inlay  made  of  twenty-five  per  cent,  platinum  solder  and  constituting  a 
part  of  the  assembled  bridge. 

Another     type     of    construction     involving    the 
Conuex  Saddle.         use   of  a   convex  instead   of  a   concave  saddle,   de- 
signed for  purely  hygienic  reasons,  may  frequently 
be  found  useful,  and  is  particularly  applicable  to  the  lower  arch  where 
considerable  absorption  has  taken  place,  and  yet  where  com[.\lete  restora- 
tion, hucco-lingually,  is  not  demanded. 

In  the  construction  of  bridges  of  this  character  a  half-tound  or  "D" 
shaped  iridio-platinum  wire  about  12  or  14  gauge,  or  smaller  if  desired, 
may  be  used,  and  the  convex  side  should  be  bent  or  swag:-d  on  a  metal 
model  to  conform  as  closely  as  possible  to  the  ridge  upon  which  it  is  to 
rest,  and  each  end  then  adapted  to  a  close  joint  with  the  cajis. 

Additional  strength  in  the  substructure  is  to  be  obtained  by  bridging 
in  between  the  connecting  bar  and  the  saddle,  especially  toward  the 
center,  with  small  pieces  of  wire,  previous  to  soldering,  and  indeed  this 
feature  is  often  essential  in  long  bridges  where  this  or  any  other  form 
of  saddle  is  employed.     (Fig.  352  A.) 

When  the  assemblage  of  the  substructure  is  completed  the  porcelain 
is  then  built  down  to  the  edges  of  the  saddle,  both  labially  and  lingually, 
but  no  effort  to  cover  it  should  be  made.     (Fig.  352  B.) 


455 

In  short  bridges,  and  especially  in  the  uppe) 
CClCSCOpC  Crowns.  arch,  where  the  first  molar  is  used  as  the  posterior 
abutment,  the  cosmetic  requirements  usually  indicate 
the  use  of  a  dowel  crown,  and  yet,  and  particularly  in  more  ex- 
tensive cases  where  the  second  or  tliird  molar  is  to  be  thus  utilized, 
it  is  often  best  to  use  a  shell  or  telescope  crown  upon  this  end  of  the 
bridge  in  preference  to  sacrificing  the  supporting  roof  to  the  extent  de- 
manded by  a  dowel  crown. 

Therefore  whenever  the  cosmetic  requirements  will  admit  of,  or 
wherever  the  mechanical  demands  seem  to  indicate  the  use  of  the  tele- 
scope crown  on  the  posterior  end,  in  conjunction  with  a  dowel  crown 
on  the  anterior  end,  such  a  type  of  construction  should  be  chosen. 


Fif 


353. 


Where  such  crowns  are  to  constitute  a  part  of 
Platinum  Crowns.  the  metal  substructure  before  the  porcelain  is  applied, 
it  is  obvious  that  they  must  be  made  of  platinum  in 
order  to  withstand  the  heat  of  the  furnace. 

Furthermore,  in  order  to  be  sufficiently  strong,  they  should  be  made 
of  at  least  28  gauge  platinum,  and  the  cusps  should  be  attached  and 
adequately  reinforced  with  25  per  cent,  platinum  solder. 

When  the  crown  has  been  completed  in  this  manner,  and  in  accordance 
also  with  the  general  requirements  as  previously  described,  the  detail  of 
procedure  up  to  the  final  assemblage  of  all  of  the  parts  is  the  same  as 
indicated  for  dowel  crowns  in  the  preceding  type  of  construction,  but,  in 
the  adjustment  of  the  connecting  bar  it  should  be  observed  that  strength 
is  insured  by  the  increased  contact  which  should  obtain  between  it  and 
the  band  of  the  telescope  crown. 

This  may  be  accomplished  in  fitting  the  bar  by  flattening  one  end  of 
the  iridio-platinum  wire  on  the  anvil  and  then  bending  it  to  conform 
closely  to  the  lingual  surface  of  the  crown,  thereby  obtaining  a  maximum 
degree  of  strength  in  its  attachment  when  soldered.     (Fig.  353.) 

Additional  reinforcement  of  the  cusps  may  also  be  obtained  by  fusing 
a  layer  of  porcelain  in  them,  from  the  inner  side,  when  baking  the  piece, 
and  if  the  color  of  the  crown  is  not  pleasing  to  the  patient,  such  a  fastidious 
objection  may  be  overcome  by  heavily  gold-plating  the  finished  piece. 


456 

The  elimination  of  any  possible  objections  which  may  be  raised  with 
regard  to  the  color  of  platinum,  together  with  the  facts  that  gold  is  doubt- 
less more  pleasing  to  the  eye ;  that  plating  is  only  temporary,  and  that  the 
use  of  the  telescope  crown  upon  such  teeth  as  are  somewhat  re- 
moved from  the  range  of  vision,  is  advantageous,  makes  the  combination 
of  porcelain  and  gold  in  the  construction  of  bridgework  highly  artistic 
and  therefore  often  eminently  desirable.     Indeed,  by  combining  the  two 


fj'^.33^.A, 


F/^.354.B. 


the  possibilities  of  porcelain  work  are  enhanced  ;  the  application  of  more 
extensive  pieces  is  made  practicable  and  the  most  csthetically  ideal  type 
uf  construction  is  achieved. 

This  combination  may  be  easily  effected  by  constructing  such  portions 
of  the  piece  as  must  go  through  the  furnace  on  a  platinum  substructure 
and  in  accordance  with  the  requirements  indicated,  and  then  subsequently 
attacliing  the  gold  j)arts  with  solder  after  the  porcelain  piece  has  been 
entirely  completed,  and  this  procedure  may  be  easily  accomplished  by 
snnply  making  some  provision  for  the  attachment  of  the  solder  in  the 
final  assemblage,  and  entirely  without  danger  of  fracturing  any  part  of 
the  porcelain. 


457 

Thus  when  it  is  desirable  to  use  a  gold  crown 
Gold  Crowns  ^^  ^^^  posterior  abutment  piece  instead  of  one  made 

as  Posterior  of  platinum,  the  procedure,  as  indicated,  is  identical 

Abutment  Pieces.  vip  to  the  point  of  investing  the  case  for  the  final 
assemblage  of  all  of  the  parts,  except  that  the 
saddle  is  previously  attached  only  to  the  platinum  cap  for  the  dowel  crown, 
at  the  anterior  end,  and  that  the  gold  crown  is  thus  allowed  to  remain 
free  and  in  situ  upon  the  model  during  the  completion  of  the  porce- 
lain part. 


F/q.354.C. 


The  platinum  substructure,  together  with  the  facings  which  are  to 
form  the  porcelain  part  of  the  piece,  are  then  removed,  invested  and 
soldered  as  indicated,  but  at  this  time  some  provision  must  be  made  for 
the  presentation  of  a  well  reinforced  surface  of  platinum  toward  the  gold 
crown,  which  will  admit  of  subsequently  attaching  the  latter  thereto  with 
gold  solder.  This  may  be  effected  by  boxing  up  the  posterior  end  of  the 
piece  with  not  thinner  than  28  gauge  platinum,  and  securely  soldering 
it  to  the  saddle,  connecting  bar  and  lingual  support  as  illustrated  in 
Fig.  354  A. 

When  thus  completed  the  porcelain  may  then  be  built  up,  carved  and 
baked,  as  desired,  and  when  this  part  of  the  piece  has  been  entirely  fin- 
ished it  should  be  replaced  upon  the  model,  attached  in  its  proper  relation 
to  the  gold  crown,  with  hard  wax,  and  the  whole  then  carefully  removed, 
invested  and  soldered  with  i8-karat  solder. 

As  the  space  between  the  porcelain  part  of  the  piece  and  the  gold 
crown,  which  is  to  be  filled  with  solder,  is  necessarily  small  (Fig.  354  B), 
the  soldering  may  be  facilitated  by  allowing  the  latter  to  be  more 
or  less  freely  exposed  in  the  investment,  and  all  danger  of  fractur- 
ing the  porcelain,  or  of  encountering  any  difficulties  in  the  procedure  will 
be  overcome  by  slowly  and  thoroughly  heating  the  case  before  attempting 
to  fuse  the  solder.  The  result  obtained  in  the  completed  case  is  shown 
in  Fig.  354  C. 


458 

Dowel  Crowns  as  Hbutmeiit  Pieces. 

Because  of  the  desirability  of  using  some  form  of  porcelain  crown 
as  abutment  pieces  on  all  of  the  ten  anterior  teeth,  and  of  the  usual 
difficulty  in  observing  such  cosmetic  requirements,  which  apply  particu- 
larly to  the  construction  of  bicuspid  crowns,  the  typical  form  of  porcelain 
crown,  supplemented  by  provision  for  admitting  of  attachment  with  solder, 
will  be  found  most  artistic  and  practicable. 

Such  a  provision  may  be  made,  and  such  crowns  may  be  used  in 
preference  to  gold  ones,  or  even  to  gold  ones  with  porcelain  facings,  with 
almost  equal  assurances  of  success  and  permanency  by  simply  increasing 
the  depth  and  thickness  of  the  platinum  extension  upon  the  lingual  edge 
of  the  cap,  which  has  been  previously  recommended  and  illustrated  in 


A 

F/(j.  255 


connection  with  the  construction  of  single  bicuspid  crowns,  though 
the  principle  is  also  equally  applicable  to  the  construction  of  a  crown  for 
molars,  cuspids,  or  incisors,  or  for  any  tooth  where  the  use  of  porcelain 
may  be  regarded  as  safe,  and  where  it  may  be  desirable  to  avoid  the 
presence  of  gold  cusps  or  backings  for  cosmetic  reasons. 

When  it  seems  warrantable  to  use  such  a  crown  as  an  abutment 
piece  the  entire  cap  should  be  made  of  not  thinner  than  28  ga.  platinum, 
and  the  lingual  extension,  which  is  added  at  the  time  of  soldering  the 
facing,  should  be  of  at  least  the  same  thickness,  and  as  wide  or  deep  on 
the  approximal  side,  presenting  toward  the  dummy  or  dummies  which  are 
to  be  subsequently  attached,  as  the  occlusion  will  admit.     (Fig.  355  A.) 

If  this  extension  is  well  reinforced  with  platinum  solder,  when  the 
crown  is  then  baked  and  comi^leted,  am])le  strength  and  opportunit)-  for 
attachment  with  solder  is  thereby  afforded,  and  a  most  artistic  abutment 
piece  is  made  possible.     (Fig.  355  B.) 

When  thus  completed  it  should  be  placed  in  ])osition  in  the  mouth 
together  with  the  other  abutment  pieces,  and  the  "bite"  and  impression 
secured,  when  the  bridge  may  be  assembled  and  soldered  as  usual. 


459 

HH  Porcelain  Dummies. 

Most  of  the  advantages  to  be  obtained  in  porcelain  bridgework  to- 
gether with  the  ehmination  of  the  ncccssily  for  a  saddle,  and  the  ad- 
vantages offered  by  gold,  may  be  achieved  in  a  most  practicable  and 
highly  esthetic  manner  with  Brewster's  bridge  teeth,  or  similar  types  of 
porcelain  dummies,  in  conjunction  with  the  above  style  of  crown  for  the 
anterior  abutment  pieces,  and  gold  telescope  crowns  for  posterior  attach- 
ments, and  it  is  safe  to  say  that  this  combination  affords  a  type  of  con- 
struction which  is  more  generally  applicable  than  almost  any  other,  and 
which  offers  opportunity  for  obtaining  the  very  acme  of  artistic  and  me- 
chanical  achievement   in  the   line   of  bridge   construction. 

Fig.  356  shows  a  typical  case  of  this  kind;  two  other  cases,  in 
one  of  which  a  porcelain  crown  on  the  cuspid  serves  as  the  anterior 
anchorage,  were  previously  illustrated  in  connection  with  the  detail 
incident  to  the  use  of  this  class  of  porcelain  "dummies"  in  Fig.  321. 


y^/y.  3Sff. 


makittd  Porcelain  Blocks. 

Because  of  the  difficulty  of  obtaining  ready-made  gum  blocks  which 
may  be  suitable  to  the  requirements  and  variations  so  frequently  de- 
manded by  the  extent  of  absorption  and  the  type  of  tooth,  and  which 
may  even  then  be  successfully  attached  to  any  form  of  abutment  pieces 
for  "fixed"  bridges  by  means  of  soldering,  the  construction  by  the  dentist 
of  special  pieces  which  will  meet  the  combined  requirements  is  not 
infrequently  desirable. 

This  may  be  accomplished  with  comparative  ease  by  first  obtaining 
good  models  with  the  caps  or  abutment  pieces  in  position,  and  then  select- 
ing suitable  long-pin  facings  for  the  entire  case.  In  anterior  cases  where 
no  saddle  is  required  these  should  be    ground  to  the  desired  adjustment 


4^0 

and  the  separate  crowns  then  completed,  after  which  the  intermediate 
facings  which  are  to  constitute  the  desired  block  should  be  assembled  with 
hard  wax,  removed  from  the  model,  and  invested.  They  should  now  be 
united  by  means  of  a  connecting  bar  of  about  i6  g.  round  iridio-platinum 
v.-ire,  placed  immediately  beneath  the  pins,  and  attached  with  25  per  cent, 
platinum  solder,  and  at  the  same  time  provision  for  subsequently  soldering 
the  finished  piece  to  the  other  part  of  the  bridge  should  be  made  by  at- 
taching a  small  piece  of  28  g.  platinum  plate  to  each  end  of  the  connecting 
bar.     (Fig.  357  A.) 

When  thus  assembled  the  piece  may  then  be  finished  with  porcelain 
and  the   required  adaptation   and  conformation  obtained  by  burnishing 


A 


Fiq.  357. 


platinum  foil  over  the  surface  of  the  model,  and  building  the  porcelain 
down  to  it.  When  completed,  the  platinum  foil  may  be  stripped  off  and 
the  piece  then  placed  in  position  on  the  model,  removed  in  its  proper  rela- 
tion to  the  attachments,  invested  and  soldered  with  18  K.  solder.     (Fig. 

357  y>-) 

'J'he  same  procedure  ajjplies  also  to  the  construction  of  blocks  where 
the  use  of  a  saddle  nia\'  be  indicated  by  tlic  rciinircinents  of  occlu- 
sion or  extensive  restoration.  In  building  sucli  blocks,  h(jvvever,  the 
saddle  should  be  adapted  in  the  ])rescribcd  manner  and  then  attached 
to  the  facings  at  the  time  of  their  assemblage  with  solder.  Fig.  358 
illustrates  the  t)pical  application  of  a  section  constructed  in  this  manner. 


461 
Building,  Carding  and  Baking. 

Whilst  the  details  incident  to  the  manipulation  and  fusing  of  porce- 
lain have  been  elsewhere  considered  at  some  length,  their  application  to 
the  construction  of  bridgework  in  particular   requires  special   emphasis. 

As  soon  as  the  metal  substructure  has  been  removed  from  the  invest- 
ment after  the  final  soldering,  it  should  be  treated  to  the  acid  bath  and 
allowed  to  remain  therein  long  enough  to  insure  the  thorough  removal 
of  all  particles  of  flux,  investment  material,  etc.,  and  then  washed  in  warm 
water  to  remove  the  acid. 


Fiq.  358. 


All  sharp  edges  of  metal,  and  projecting  ends  of  pins  throughout  the 
piece  should  now  be  finished  down  with  small  carborundum  stones,  used 
in  the  engine,  and  then  with  disks,  until  smooth  and  nicely  rounded, 
when  the  metal  substructure  is  ready  for  the  porcelain.  Failure  to 
observe  this  detail  will  be  apt  to  result  in  unnecessarily  diminishing  the 
strength  of  the  finished  piece,  or  in  the  appearance  of  small  checks  in  the 
porcelain  near  its  junction  with  the  substructure,  both  of  which  may  be 
attributed  to  the  presence  of  sharp  angles  or  edges  of  metal. 


462 

When    thus    finished    and    again    washed    thor- 
Building  Body.  oughly  in  order  to  remove  debris,  the  piece  should 

be  grasped  in  a  small  pin-vise  and  the  porcelain  body, 
mixed  with  distilled  water  to  as  thick  a  consistency  as  it  may  be  used,  and 
thoroughly  spatidatcd,  then  applied  and  carefully  worked  down  into  the 
most  minute  crevice.  To  obtain  the  maximum  of  strength  in  the  fused 
porcelain  the  "body"  should  be  packed  as  thoroughly  as  possible  and  air 
spaces  must  be  avoided.  As  this  procedure  is  continued  and  the  piece  is 
gradually  built  up  to  the  desired  form,  the  surplus  moisture  may  from 
time  to  time  be  removed  with  a  small  piece  of  linen  or  blotting  paper  held 
between  the  thumb  and  finger,  some  degree  of  pressure  being  used. 

When  ample  proportions  to  admit  of  shaping  to  the  required  con- 
formation obtain,  the  mass  may  then  be  passed  over  a  flame,  or  held  near 
the  heated  furnace  for  a  few  moments  until  dry  enough  to  admit  of  carv- 
ing nicely  without  crumbling. 

With  a   suitable   instrument,   such  as  has  been 

C^rvinfl.  previously    illustrated   in   the   chapter   on    Porcelain 

Crowns,   the   "body"   should   now   be   given  definite 

form,  and  carved  until  each  tooth  is  more  or  less  distinctly  shaped,  and 

until  the  desired  occlusion  and  general  outline  for  the  finished  piece  is 

obtained. 

This  may  be  observed  by  carefully  removing  the  piece  from  the  pin- 
vise  and  placing  it  upon  the  model,  on  the  articulator,  and  in  the  event  of 
the  "body"  becoming  too  dry  to  be  handled  it  may  be  slightly  moistened 
with  water  by  means  of  a  small  brush. 

When  the  piece  has  been  suitably  carved  it  should  then  be  noted  that 
no  thin  frail  edges  of  porcelain  overlap  upon  the  metal,  as  such  parts  will 
invariably  fracture  in  cooling,  or  be  broken  off  either  before,  during  or 
soon  after  mounting,  and  it  should  also  be  noted  that  the  interior  of  the 
abutment  pieces  and  the  under-surfaces  of  saddles  are  clean  and  free  from 
particles  of  porcelain,  which,  after  fusing,  might  interfere  with  the  subse- 
quent adjustment  of  the  piece. 

While  it  is  desirable  to  use  but  one  grade  of  "body"  throughout  the 
piece,  for  the  reasons  previously  mentioned,  a  more  artistic  result  is 
usually  to  be  obtained  by  selecting  a  darker  color  for  the  first  bake,  and 
then  finishing  with  a  color  which  closely  matches  that  of  the  facings, 
thus  obtaining  a  blend  of  the  two  which  results  in  a  darker  effect  toward 
the  base  and  down  in  the  grooves  and  pits  of  the  finished  piece. 

When  the  piece  is  thus  ready  for  the  first  bake 

Baking.  it  should  be  adjusted  to  some  form  of  fire-clay  sup- 

]Kjrt  which  will  cause  it  to  maintain  a  perpendicular 


4^3 

position  and  securely  support  it,  and  then  placed  in  front  of  the  slightly 
heated  muffle  where  it  should  be  allowed  to  remain  until  thoroughly  dry. 

In  placing  the  piece  in  the  furnace  it  must  be  observed  that  it  is 
free  from  contact  with  the  walls  of  the  muffle,  as  too  close  proximity 
thereto  frequently  results  in  burning  the  color  out  of  the  facings,  and 
direct  contact  would  be  likely  to  fracture  them. 

It  should  also  be  noted  that  the  piece  is  placed  cross-wise  in  the 
muffle  in  order  that  a  uniform  heat  may  obtain  throughout,  as  this 
varies  appreciably  in  all  open-end  furnaces,  and  uniformity  is  imperative. 
And  further  it  is  usually  best  to  allow  the  porcelain  part  of  the  piece  to 
present  toward  the  door  of  the  muffle  as  by  this  means  the  fusing  of 
the  "body"  may  be  observed  during  the  process. 

The  muffle  should  then  be  closed  and  the  temperature  gradually  in- 
creased until  fusing  begins,  but  for  the  first  bake  the  body  should  only 
be  fused  to  a  high  "biscuit/'  or  until  a  close  coalescence  of  the  particles 
has  taken  place.  This  will  leave  the  surface  somewhat  granular,  but  in- 
sures a  degree  of  shrinkage  which  is  most  favorable  both  to  strength,  and 
to  the  completion  of  the  piece  in  two  bakings. 

When  the  baking  is  thus  completed  the  heat  should  be  immediately 
shut  off,  and  the  case  then  allowed  to  remain  in  the  muffle  until  cool 
enough  to  remove  therefrom  without  danger  of  checking  the  facings. 

When  sufficiently  cool  to  admit  of  handling,  the  piece  should  then 
be  removed  and  again  adjusted  to  the  pin-vise.  Distilled  water,  applied 
with  a  small  brush,  should  now  be  carefully  worked  down  into  all  crevices 
and  spaces  presenting  as  a  result  of  the  shrinkage,  as  a  means  of  assisting 
in  carr}-ing  the  body  well  down  into  places  which  might  otherwise  be 
difficult  to  completely  fill. 

Well  mixed  "body"  of  the  proper  color  and  consistency  should  now 
be  applied  with  the  point  of  the  carving  instrument  and  carefully  worked 
down  into  all  such  spaces  by  jolting  with  the  serrated  edge,  and  when 
these  are  well  filled  the  surplus  moisture  should  be  absorbed,  and  the  full 
outhne,  contour  and  occlusion  restored,  when  the  piece  is  ready  for  the 
second  bake. 

If  the  first  bake  was  carried  to  the  point  of  shrinkage  and  vitrifica- 
tion indicated,  and  the  body  was  closely  packed,  two  bakes  will  usually 
be  all  that  is  required  to  complete  th.e  case,  but  the  second  bake  should, 
of  course,  be  carried  to  the  point  of  complete  vitrification,  and  be  heated, 
and  allowed  to  cool,  in  the  same  njanner. 

In  cases  where  gum  restoration  demands  the  presence  of  pink 
enamel,  that  may  be  used  at  this  time  also  provided  its  fusing  point  is 
approximately  the  same  as  that  of  the  basal  body,  but  if  it  should  be  of 


464 


the  low  fusing  variety,  and  a  higher  fusing  body 
used  for  the  base,  a  third  or  separate  baking  will, 
of  course,  be  necessary. 

In  the  event  of  imperfections  after  the  second 
bake,  a  third,  or  possibly  even  a  fourth,  bake  may 
be  required,  and  in  such  instances  the  lower  fusing 
enamels  can  be  used  to  advantage  whenever  the 
proper  color  may  be  obtained. 

If  the  body  has  been  each  time  closely  packed, 
and  at  no  time  overfused,  any  grinding  which  ma}' 
be  demanded  by  the  desired  adjustment  can  be  done 
with  impunity,  but  such  surfaces  should  afterward 
be  highly  polished  with  fine  disks. 


Ficj.  359. 


finjsbiitg 

For  the  reason  that  so  little  metal  is  exposed, 
the  finishing  of  porcelain  bridgework  is  usually  a 
very  simple  procedure,  and  yet  even  though  be)'ond 
the  range  of  vision  all  the  surfaces  of  platinum 
which  are  not  covered  by  porcelain  should  be  well 
finished  with  stones  and  disks,  and  then  highly  pol- 
ished on  the  lathe  in  the  usual  manner,  in  order  that 
the  work  may  possess  every  possible  artistic  and 
hygienic  property. 

A  more  finished  appearance  may  then  be  obtained 
by  gold-plating,  and  such  a  procedure  is  particularly 
indicated  in  cases  where  the  platinum  may  be  ex- 
posed to  view,  and  also  where  both  gold  and  porce- 
lain are  combined  in  one  piece. 

Repairingo 

The  repair  of  porcelain  bridgework  is  usually  at- 
tended with  many  difficulties,  the  i)rincipal  one  being 
the  removal  of  the  piece  when  mounted  with  cement. 
As  this  becomes  imperative,  however,  it  must  be 
effected  irrespective  of  the  mounting  medium,  and 
therefore  wlien  cemeiit  has  been  used,  some  fur- 
ther mutilation  of  the  piece  must  be  expected,  and 
is  usually  unavoidable.    To  encounter  these  difficul- 


465 

ties,  however,  will  serve  as  an  object  lesson  and  show  why  porcelain 
bridges  in  general  and  dowel  crowns  in  particular,  should  never  be 
mounted  with  cement  alone.  In  the  removal,  if  telescope  crowns  are 
present,  their  attachment  to  the  roots  should  be  destroyed  first,  and  this 
can  usually  be  accomplished  in  the  most  expedient  manner  by  the  method 
illustrated  in  Fig.  1 14.  The  detachment  of  dowel  crowns  is,  of  course, 
more  difficult,  but  these  may  usually  be  loosened  by  protecting  the  por- 
celain with  pads  of  cotton  in  the  form  of  rolls,  grasping  the  piece  with 
heavy  pliers  or  forceps,  and  then  gradually  working  it  until  the  attach- 
ment of  each  abutment  piece  is  broken,  or,  a  very  ingenious  and  most 
useful  instrument  adapted  to  this  particular  purpose,  designed  by  Dr. 
C.  G.  Morrell,  of  Chicago,  and  illustrated  in  Fig.  359,  may  be  used  by 
hooking  the  beak  over  the  edge  of  the  band,  and  then  pounding  against 
the  other  end  with  the  cylindrical  weight. 

After  removing,  all  remaining  particles  of  cement,  gutta-percha,  etc., 
should  first  be  cut  away  with  burs  and  the  case  then  placed  in  the  acid 
bath.  This  should  be  followed  by  w'ashing  it  thoroughly  in  tepid  water 
in  which  has  been  dissolved  a  liberal  quantity  of  sodium  bicarbonate,  after 
which  it  should  be  allowed  to  dry  thoroughly. 

The  remaining  accumulations  of  organic  products  must  then  be  re- 
moved before  any  effort  to  effect  repair  is  attempted,  and  this  may  be 
accomplished  by  placing  the  piece  in  the  furnace,  before  heating  the 
muffle,  and  then  turning  on  the  heat  Z'cry  sloz>.'ly  at  first,  until,  by  gradu- 
ally and  carefully  increasing  it  to  a  low  red  heat,  all  organic  matter  may 
be  burned  out. 

As  a  means  of  preventing  too  rapid  heating,  and  the  possibility  of 
fracturing  the  facings,  or  otherwise  injuring  the  case,  it  may  be  entirely 
submerged  in  an  investment,  compounded  largely  of  asbestos,  previous 
to  placing  it  in  the  furnace,  and  then  subjected  to  the  same  degree  of  heat 
in  the  same  manner.  While  a  safe  precaution,  this  is  unnecessary,  how- 
ever, in  small  pieces  or  single  crowns. 

After  this  procedure  has  been  observed,  repairs  may  then  be  effected 
in  the  ordinary  manner  and  without  subsec|uent  danger. 


Removable  BriddeworK. 


CHAPTER  XX YL 

Advantages,  Attachments.     Clasps:  Clasps  Adjusted  to  Gold  Crowns,  Typical  Appli- 
cation of  Clasps,  Clasps  Applied  to  Porcelain  Work,  The  Bryant  Clasp 
Attachment,    Peeso's    Methods,    Tube    and    Split-Post    Attach- 
ment, Crown  and  Split-Post,  Interlocking  Occlusal  Rest. 


As  designated  in  the  chapter  on  Classification,  etc.,  "removable" 
bridgework  embraces  that  type  of  construction  wherein  the  piece  which 
supports  the  missing  teeth  is  sustained  in  position  by  contact  between  it 
and  the  contiguous  soft  tissue,  supplemented  by  some  form  of  mechanical 
attachment  to  remaining  natural  teeth  which  will  afford  a  means  of  tem- 
porary fixation  and  stability,  and  yet  admit  of  the  ready  removal  and 
replacement  of  the  piece  without  disturbing  the  integrity  of  any  of  its 
parts. 

Since  the  principal  objection  to  the  employment  of  "fixed"  bridge- 
work  lies  in  the  unsanitary  condition,  which,  to  a  greater  or  less  extent, 
usually  presents  as  a  result  of  the  application  of  permanently  anchored 
pieces,  and  of  the  inaccessibility  of  some  of  their  surfaces ;  and  since  the 
importance  of  oral  hygiene  is  now  so  fully  recognized,  any  methods  of 
procedure  which  will  promote  this,  will  always  occupy  a  more  or  less 
unlimited  sphere  of  usefulness,  and  be  welcomed  alike  by  the  con- 
scientious, progressive  operator  and  the  appreciative  and  cultured  patient. 

Compared  with  "fixed"  bridgework  it  is  there- 

JldvantagCS.  fore   obvious   that   this   type   of   construction   offers 

several  features  of  advantage,  and  these  may  be 
classified  as  follows :  First,  and  most  important,  the  hygienic  properties 
to  be  derived  from  opportunity  to  remove  and  cleanse  the  piece.  Second, 
adaptability  to  varying  conditions  of  absorption,  occlusion  and  support, 
which  affords  a  greater  range  of  application.  Third,  opportunity  for 
restoring  lost  tissue  in  cases  of  extensive  absorption,  thus  making  pos- 


467 

sible  more  natural  and  more  artistic  results.  Fourth,  because  of  the  sup- 
port derived  from  contact  with  the  soft  tissues,  fewer  abutment  teeth  are 
mechanically  required.  Fifth,  unless  crowns  are  used  less  mutilation 
of  the  supporting  teeth  is  generally  involved  or  demanded.  Sixth,  a 
greater  longevity  of  those  so  employed  is  usually  insured  by  the  main- 
tenance, to  a  greater  extent,  of  their  natural  mobility. 

From  a  careful  analysis  of  these  advantages  it 

Indications.  would    seem    that   the    indications    for    the    selection 

of  this  type  of  construction  must  be  more  or  less 
general,  and  that  its  application  would  in  turn  be  quite  universal.  While 
this  is  true  to  a  large  extent,  still  "removable"  bridgework  will  perhaps 
never  entirely  supersede  "fixed"  structures,  and  though  doubtless  more 
generally  applicable,  there  will  nevertheless  be  opportunities  for  the  suc- 
cessful utilization  of  each  type  in  its  proper  place,  and  the  selection  of  the 
one  best  adapted  will  be  largely  a  matter  of  judgment  and  discrimination. 

As  a  general  rule,  however,  it  is  safe  to  conclude  that  "removable" 
structures  are  indicated  in  those  cases  where  the  conditions  and  require- 
ments are  unfavorable  to  the  reliance  upon  "fixed"  pieces. 

Specifically  this  would  confine  the  application  to  two  general  classes 
of  cases ;  first,  to  those  which  demand  the  replacing  of  several  teeth, 
and  the  restoration  of  considerable  lost  tissue ;  and,  second,  to  those  cases 
where  the  lumiber,  position  in  the  arch,  and  strength  of  the  remaining 
natural  teeth  are  unfavorable  to  the  mechanical  demands  of  a  "fixed" 
structure. 

The  former  class  would  thus  include  extensive  bridges,  or  those  de- 
manding the  use  of  a  "saddle"  of  such  proportions  as  to  admit  of 
the  required  restoration,  and  at  the  same  time  demand  removal  as  a 
means  of  sanitation ;  while  the  latter  class  w^ould  include  those  cases  in 
which  the  utility  of  the  remaining  natural  teeth  is  questionable,  or  is 
inadequate  to  the  mechanical  requirements  because  of  looseness,  or  of 
being  too  far  apart  or  otherwise  unfavorably  located  in  the  arch,  and 
where  some  form  of  support  by  means  of  contact  with  the  intervening 
soft  tissue  is  therefore  required. 

Incident  to  the  application  and  construction  of 
KC(1Uil*CniCnt$.  removable  bridges  the  requirements  demand,  first,  a 

close  adaptation  of  the  body  of  the  piece  to  the  soft 
tissue  upon  which  it  is  to  rest;  and,  second,  a  means  of  attachment  to  the 
supporting  teeth  which  will  admit  of  easy  adjustment  in  removing  and 
replacing  the  piece ;  afi:'ord  a  reasonable  degree  of  stability  and  durability, 
and  vet  permit  some  slight  mobility  when  in  jiosition  in  the  mouth  ;  and 
which  will  further  possess  sufficient  inherent  strength  to  insure  reason- 
able permanency. 


468 

Thus  like  "fixed"  bridge  work  it  is  apparent  that  the  successful 
application  and  general  utility  of  "removable"  structures  is  also  largely 
a  problem  of  anchorage,  or  attachment  to  the  supporting  teeth. 

This  problem  has  engaged  the  attention  of  the  profession  for  a 
number  of  years,  and  as  a  result  innumerable  methods  of  attachment  to 
the  remaining  natural  teeth,  which  would  be  an  improvement  upon  the 
more  simple  and  ordinary  form  of  clasps,  have  been  devised. 

Many  of  these  have  been  proclaimed  a  dental  desideratum,  and 
have  been  heralded  to  the  profession  as  a  means  of  revolutionizing  the 
construction  of  all  forms  of  partial  dentures,  only  to  be  subsequently 
abandoned,  as  impracticable,  because  of  being  entirely  too  intricate,  or 
as  worthless,  because  of  a  lack  of  strength. 

€la$p$. 

Some  form  of  clasps,  however,  when  properly  adapted,  is  still  to  be 
regarded  as  the  most  simple  attachment,  and  while  its  indiscriminate  em- 
ployment or  its  faulty  adaptation  may  frequently  prove  injurious  to  the 
supporting  tooth,  or  may  sometimes  even  cause  its  loss,  the  fault  lies 
more  often  with  the  operator  than  with  the  principle. 

In  the  adaptation  of  simple  clasps  to  the  crowns 
RCflUircmcntS.  of  natural  teeth  an  observation  of  the  following  re- 

quirements will  increase  the  opportunities  for  obtain- 
mg  successful  results. 

First.  Where  several  natural  teeth  remain,  in  determining  which 
ones  to  clasp,  those  should  be  selected  which  are  of  the  most  favorable 
shape,  stability  and  position  in  the  arch,  and  with  approximately  parallel 
axes,  and  as  nearly  opposite  in  their  relation  to  each  other  as  possible. 
Extensive  experience  has  shown  that  the  bicuspids  ofifer  the  most 
favorable  shape  for  the  adaptation  of  clasps ;  that  the  molars  rank  next  in 
order,  and  that  the  cuspids  and  incisors,  respectively,  are  least  favorable. 
Indeed,  clasps  upon  any  of  the  six  anterior  teeth  are  rarely  ever  indicated, 
and  seldom  practicable. 

Second.  The  clasp  should  always  be  made  of  an  alloy  especially 
prepared  for  this  purpose  because  of  the  necessity  for  a  degree  of  springi- 
ness, or  resiliency,  which  will  admit  of  some  expansion  and  yet  offer 
sufficient  resistance  to  return  to  its  original  form,  and  to  thus  insure  a 
firm  grasp  upon  the  tooth.     (See  chapter  on  Metals  and  Alloys.) 

Third.  It  should  be  heavy  or  thick  enough  to  more  or  less  per- 
manently retain  its  form,  for  which  reason  nothing  thinner  than  from  26 
to  28  gauge  should  be  used. 


469 

Fourth.  In  adapting  it  to  the  tooth  the  clasp  should  be  as  wide  as 
possible,  not  to  interfere  zvith  the  occlusion  or  impinge  upon  the  gum 
tissue  (Fig.  360  A),  and  it  should  encircle  at  least  three  angles  of  the 
tooth's  circumference.     (Fig.  360  B.) 


LAB/41.    V/EW 


LABIAL     VIEW 


LINGUAL     V/EW 


A 


LINGUAL    VIEW 


Ficj.  360. 


A  wide  clasp  is  preferable  to  a  narrow  one,  for  the  reason  that  it  will 
thus  encompass  the  most  bulbous  portion  of  the  tooth,  and  be  sustained 
in  its  relation  thereto  by  frictional  contact  at  a  few  points. 


470 

Such  a  contact  is  desirable  and  advantageous  because  the  possibiHties 
of  mechanical  abrasion  and  ultimate  disintegration  of  the  enamel  there- 
from, or  from  chemical  dissolution,  as  compared  with  a  narrow  clasp 
\Yhich  is  necessarily  more  closely  adapted  to  the  walls  of  the  tooth,  are 
thereby  diminished ;  and  it  is  necessary  that  it  should  encircle  at  least 
three  angles  in  order  that  both  ends  may  grasp  the  tooth  in  such  manner 
as  to  sustain  it  in  position  thereon. 

Fifth.  In  effecting  this  adaptation  a  plaster  impression  of  the 
crown  of  the  particular  tooth  to  be  clasped  (Fig.  361 -A)  should  first  be 
obtained  and  then  properly  built  up,  so  as  to  allow  the  pouring  of  a  fusible 


a 


Fi(^.  361. 


alloy  model,  showing  just  the  teeth  to  be  clasped.  (Fig.  361 -B.)  The 
clasp  should  then  be  primarily  formed  and  trimmed  to  the  proper  outline 
on  the  model,  which  may  be  done  with  ease  because  of  its  indestructibility. 
It  should  then  be  placed  in  position  on  the  natural  tooth  and  the  adapta- 
tion perfected  in  the  mouth,  after  which  the  final  impression  for  the 
attachment  of  the  clasp,  or  clasps,  to  the  base  should  be  taken  with  them 
in  position.  The  most  accurate  method  is  to  take  a  separate  impression 
for  each  clasp,  attaching  them  to  the  base  one  at  a  time. 

Sixth.  If  the  attachment  is  to  be  made  to  a  metal  base  by  soldering, 
the  impression,  with  the  base  and  clasps  in  position,  should  be  filled  with 
a  small  quantity  of  investment  material,  so  that  when  separated  the  solder- 
ing may  be  done  directly  on  the  model,  thus  insuring  the  preservation  of 
the  proper  relation. 

When  the  case  is  to  be  of  vulcanite,  however,  the  impression  should  be 
filled  with  plaster,  anrl  when  the  model  is  obtained  the  clasps  may  be 
carefully  detached  therefrom,  and  anchorage  pins,  or  projections,  then 


4/1 

soldered  to  them  at  the  proper  points,  after  which  they  should  be  re- 
placed on  the  model  (Fig.  362)  and  the  case  finished  as  usual. 

Seventh.  In  the  attachment  of  the  clasp  to  the  base  whether  it  be 
done  by  direct  soldering  thereto,  as  in  the  case  of  gold  or  platinum  bases, 
or  by  the  addition  of  pins,  or  projections  for  attachment  to  vulcanite,  it 
must  be  observed  that  no  interference  with  the  spring  of  the  clasp  is 


F/a  3  62. 


offered  in  either  instance,  and  that  each  end  is  allowed  to  remain  free 
from  any  contact  or  attachment  which  would  impair  its  grasp  of  the  tooth, 
and  thus  destroy  its  effectiveness  as  a  clasp. 

It  is  also  necessary  to  observe  that  the  attachment,  or  provision  for 
attachment,  be  made  at  a  point  approximating  a  nearly  perpendicular  sur- 
face of  the  crown  of  the  tooth  supporting  it,  or,  in  other  words,  at  a  point 
where  no  spri}ig  in  the  clasp  will  he  required  in  adjusting  the  piece  to 
position. 


4/2 

Also  it  must  be  further  observed  that  adequate  strength  in  the  attach- 
ment of  the  clasp  to  the  base  be  insured.  This  is  a  very  important  feature, 
as  clasps  are  subjected  to  considerable  stress,  when  in  use,  as  well  as  when 
the  piece  is  being  removed  or  replaced,  and  it  is  therefore  necessary  to 
make  every  provision  for  obtaining  the  highest  possible  degree  of  strength 
in  the  attachment. 

While  the  use  of  narrow  clasps,  made  of  ordin- 

TnjuriOUS  Effects.        ary  clasp  metal,  or  in  the  form  of  small  round  wire 

doubled  upon  itself,  or  of  half-round  wire  with  the 

flat  side  adapted  to  the  tooth  is  sometimes  recommended,  any  form  of 

narrow  clasp,  such  as  is  illustrated  in  Fig.  363,  when  adapted  to  the 

natural  tooth,  is  usually  to  be  condemned  for  the  reason  that  the  narrower 


F' ^1-363.  Fit;.  364. 


it  is  the  closer  it  fits,  or  hugs,  the  tooth ;  and  the  closer  it  fits  the  tooth  the 
more  mechanical  abrasion  it  causes ;  and  the  more  abrasion  it  causes  the 
more  injury  it  does. 

For  the  same  reason  the  practice  of  first  making  the  clasp  of  pure 
gold  well  adapted  to  the  tooth,  and  then  fitting  clasp-metal  over  this  and 
attaching  the  two  with  solder,  is  to  be  discouraged,  particularly  when  the 
application  is  to  be  made  to  the  natural  crown. 

Indeed,  when  simple  clasps  are  to  be  used,  and  when  they  are  to  be 
supported  by  the  natural  crown  of  the  tooth,  those  made  in  accordance 
with  the  above  requirements,  and  sustained  by  frictional  contact  at  a  few 
points  only,  will  be  found  to  serve  the  purpose  better,  and  to  do  less  in- 
jury to  the  tooth  than  any  of  the  latter  forms. 

Injury  to  the  gum  tissue  surrounding  the  necks  of  all  of  the  remain- 
ing natural  teeth  is  also  quite  common  in  cases  where  simple  removable 
appliances  in  the  form  of  either  "bridges"  or  "partial  plates"  which  rest 
entirely  upon  tlie  gum  are  worn.  As  a  result  of  the  continued  irritation 
caused  by  the  constant  riding  of  the  piece  upon  tlie  necks  of  these  remain- 
ing teeth,  considerable  gingival  inflammation  is  usually  present,  and  in 


473 

many  instances  this  becomes  so  severe  as  to  result  in  the  ultimate  loosen- 
ing', or,  possibly,  in  the  loss  of  the  teeth. 

Such  a  casualty  may  be  more  or  less  entirely  overcome,  however, 
and  any  great  extent  of  subsequent  settlement  precluded,  by  providing 
a  rest  which  will  cause  the  piece  to  ride  largely  upon  the  supporting  teeth 
instead  of  on  the  gum  tissue. 

As  a  means  of  overcoming  this  possibility,  and 
CbC  Bonwill  Clasp.      of    also    diminishing    the    devastating    influence    of 
abrasion  resulting  from  the  adaptation  of  the  usual 
form  of  clasps,  and  of  further  obtaining  increased  stability  in  their  attach- 
ment to  the  tooth,  an  occlusal  rest  constituting  a  part  of  the  clasp  was 
early  advocated  by  Dr.  W.  G.  A.  Bonwill.     (Fig.  364.) 


f^icf.  365. 

This  type  of  clasp  is  still  frequently  used,  often  indicated  and  usually 
productive  of  good  results.  In  constructing  such  clasps  the  occlusal  rest 
should  be  made  of  a  sufficiently  strong  material — plate  or  half-round  wire 
— bent  to  the  proper  form,  and  subsequently  attached  to  the  clasp  by 
means  of  solder,  and  the  end  should  rest  in  and  conform  to  the  sulcus  of 
the  tooth  so  as  not  to  interfere  with  the  occlusion  of  the  opposing  teeth. 

Greater  strength  and  a  more  secure  fixation  of 
ClASps  with  Occlusal  the  piece  when  in  position  may  be  obtained  by  insert- 
Rc$t$  In  Tillings.  ing  a  filling  and  allowing  the  projecting  end  of  the 
occlusal  rest,  which  should  be  similarly  attached  to 
and  thus  become  a  part  of  the  clasp,  to  fit  snugly  into  a  socket  cut  for  its 
accommodation  into  the  body  of  the  filling  as  previously  described  and 
illustrated  in  connection  with  simple  rests  for  "fixed"  bridges  in  Fig.  261. 

Indeed,  whenever  it  may  possibly  be  applied,  this  method  of  forming 
a  clasp  attachment  for  "removahh"  bridges,  and  particularlv  the  pro- 
cedure suggested  by  Dr.  Ottolengui,  which  has  been  fully  described,  is  to 
be  regarded  as  among  the  most  useful  and  highly  practicable  of  all 
similar  processes.  (Fig.  365.)  When  two  are  employed  on  the  same 
fixture,  however,  absolute  parallelism  must  of  course  obtain. 


474 

Clasps  Jldjustcd  to  Gold  £rowti. 

Because  of  the  injury  to  the  natural  crown  of  a  tooth  supporting  a 
clasp  which  usually  occurs  to  a  greater  or  less  extent  in  time,  and  as  a 
result  of  abrasion  and  chemical  dissolution,  it  may  often  be  desirable  to 
first  place  a  gold  crown  upon  the  tooth,  and  then  adjust  the  clasp  to  it, 
for  by  this  means  the  possibility  of  subsequent  disintegration  of  the  natural 
crown  is  entirely  eliminated ;  a  perfect  adaptation  and  a  more  secure 
mechanical  adjustment  is  made  possible  and  greater  permanency  is 
insured. 


A 


EIcj.  366, 

In  the  construction  of  a  crown  which  is  to  be  used  for  this  purpose, 
however,  two  features  should  be  observed.  First,  it  should  be  made 
heavy  enough  to  withstand  the  continued  friction  from  contact  with  the 
clasp,  and  second,  no  great  degree  of  lateral  contour  should  be  given  to 
its  form. 

In  observing  the  first,  a  form  of  gold — such  as  platinised  gold  which 
is  somewhat  harder  or  tougher  than  the  ordinary  plate  should  be  used  for 
the  band,  and  it  should  be  at  least  28  ga.  in  thickness.  The  second  re- 
quirement should  obtain  in  order  to  admit  of  a  close  telescoping  adjust- 
ment of  the  clasp  to  the  crown,  and  to  facilitate  the  removal  and  replace- 
ment of  the  piece,  both  of  which  would  be  more  or  less  impaired  if  much 
contour  prevailed. 

In  adjusting  the  clasp  to  the  crown  it  should  be  adapted  in  accord- 
ance with  the  preliminary  requirements  in  so  far  as  size,  form  and  rela- 
tion are  concerned,  and  if  simple  clasps  are  used  this  may  be  done  after 
mounting  the  crown,  or  crowns. 


475 

An   occlusal   rest  is   also   equally   applicable  to 
Clasps  with  Occlusal     S^^^  crowns,  and  will  add  much  to  the  stability  of 
KestS  Jlpplied  to        the  piece.     This  may  be  obtained  in  the  most  simple 
Gold  Crowns.  manner  by  following  the  procedure  described  in  con- 

nection with  the  Bonwill  Clasp. 
Or,  if  still  greater  stability  is  desired  a  socket  for  the  reception  of 
an  interlocking  rest  may  be  made  in  the  crown,  and  the  rest  adapted  and 
adjusted  to  this  as  suggested  in  its  application  to  fillings,  and  then  at- 
tached to  the  clasp. 

In  this  procedure  the  socket  in  the  crown  should  be  made  after  the 
cusps  have  been  attached  but  before  they  are  reinforced.  This  may  be 
easily  accomplished  by  cutting  into  the  crown  at  the  proper  point  and  to 
the  desired  dimensions ;  fitting  an  "L"  shaped  piece  of  gold  into  this,  thus 
forming  a  box  (Fig.  366-A),  and  then  completing  the  soldering  and  re- 
inforcement of  the  cusps  (Fig.  366-B),  after  which  the  rest  should  be  ac- 
curately fitted  therein,  and  then  soldered  in  its  proper  relation  to  the 
clasp,  when  the  crown  may  be  mounted,  and  the  impression  subsequently 
taken  with  the  finished  clasp  or  clasps  in  position,  as  indicated. 

CVPical  JTpplicdtion  of  €la$p$. 

While  clasps  are  more  or  less  generally  applicable  to  a  large  variety 
of  conditions,  and  particularly  to  the  support  of  all  forms  of  partial 
dentures  where  natural  posterior  teeth  remain  on  both  sides  of  the  arch, 
there  are  nevertheless  certain  cases  where  they  are  especially  useful. 

A   type   of   cases   which   is   quite   common   and 

Cower  Cases.  which  will  serve  to  illustrate  one  of  the  most  prac- 

ticable applications  of  clasps,  irrespective  of  whether 
they  are  adapted  to  the  natural  crowns  of  teeth,  or  to  gold  crowns,  is 
where  the  replacement  of  the  lozver  bicuspids  and  molars  is  demanded. 

This  condition,  while  more  or  less  simple,  is  encountered  so  often  as 
to  require  the  very  best  type  of  construction,  and  this  is  usually  to  be 
accomplished  by  first  making  the  clasps  and  then  taking  the  impression 
with  them  in  position  on  the  teeth.  When  the  model  with  the  clasps  in 
place  is  then  obtained,  a  piece  of  14  ga.  round  iridio-platinum  wire  should 
be  conformed,  by  means  of  pliers,  to  the  outline  of  the  anterior  part  of  the 
arch  at  a  point  well  down  toward  the  fioor  of  the  mouth. 

When  this  adjustment  is  obtained  the  end?  of  the  wire  should  be 
flattened  on  the  anvil  and  then  bent  to  conform  to  the  requirements  of  at- 
tachment to  the  base. 


476 

If  metal  bases  are  used  they  should  be  swaged  and  fitted  previous  to 
taking  the  impression,  and  should  be  in  position  in  the  mouth — together 
with  the  clasps — when  this  is  done.  The  impression  should  then  be  taken 
in  the  same  manner  as  indicated  for  "saddles"  in  fixed  bridgework. 

The  flattened  ends  of  this  heavy  wire  should  now  be  bent  to  come  in 
contact  with  the  saddle  and  then  waxed  in  place,  removed,  invested  and 
soldered  thereto.  When  this  is  accomplished  a  projection  of  the  same 
wire,  slightly  flattened,  or  of  heavy  clasp  metal  should  then  be  fitted  to 


Fiq.  367. 


extend  from  the  wire  to  the  clasps  and  securely  sustained  in  position  with 
hard  wax.  The  whole  should  now  be  carefully  detached  from  the  model 
and  invested  and  then  soldered  (Fig.  367),  after  which  the  teeth  may  be 
attached  with  vulcanite  and  the  case  then  finished. 

If  the  bases  are  to  be  made  of  vulcanite,  or  when  aluminum  is  used, 
the  procedure  is  the  same  except  that  the  flattened  ends  of  the  wire  should 
be  adapted  to  the  model  in  such  manner  as  to  admit  of  being  subsequently 
well  surrounded  with  rubber,  and  then  notched  with  a  file  so  as  to  insure 
mechanical  retention  and  strength  in  the  attachment,  after  which  the 
clasps  should  be  attached  with  solder  in  the  manner  indicated  (Fig.  368), 
and  the  case  then  finished  as  usual.     (Fig.  369.) 

The  employment  of  wire  in  this  manner  offers  greater  strength  and 
less  obstruction  to  the  tongue;  less  irritation  and  consequent  injury  to 


477 


00 


478 

the  gum  tissue  surrounding  the  remaining  anterior  teeth,  thus  increasing 
their  durability,  and  insures  a  more  absolutely  hygienic  condition  than 
may  be  obtained  in  other  methods. 

By  a  similar  mode  of  procedure  these  same  ad- 

Uppct*  0a$C5.  vantageous  features  are  frequently  to  be  obtained  in 

construction  of  upper  cases  involving  the  replacement 

of  some  of  the  posterior  teeth,  but  where  at  least  one  remains  on  each 

side. 


He,. 


370. 


In  such  cases  if  the  piece  may  be  constructed  of  gold  with  vulcanite 
attachment  for  the  teeth,  or  of  platinum  and  porcelain,  the  covering  of  a 
very  small  portion  of  the  palate  will  be  required,  and  all  contact  with 
the  necks  of  remaining  natural  teeth  may  be  avoided  (Fig.  371),  while  if 
vulcanite  is  used  throughout,  a  greater  area  of  the  palate  must  of  course 
be  covered  in  order  to  insure  sufficient  strength,  though  contact  with  the 
necks  of  teeth  may  not  be  necessary.     (Fig.  371.) 

As  applied  to  gold  or  platinum  the  base  corresponding  in  size  with 
that  outlined,  should  be  swaged  of  at  least  28  ga.  material,  and  fitted. 
The  narrow  connecting  transverse  portion  which  extends  across  the 
palate  should  be  well  reinforced  by  soldering  thereto  an  additional  piece 
of  the  same  gauge,  but  somewhat  narrower,  also  swaged  between  the  same 
dies. 


479 

This  insures  adequate  strength  in  the  base  and  when  thus  rein- 
forced, the  clasps  should  be  fitted,  the  impression  taken  and  their  attach- 
ment then  secured  in  the  manner  indicated,  after  which  the  case  may  be 
completed  by  attaching  the  teeth. 

While  the  illustration  shows  the  clasps  adapted  to  the  bicuspids,  in 
similar  cases  they  may  be  placed  upon  the  molars.  Indeed  this  would 
usually  be  preferable  provided  the  shape  and  vertical  pose  of  the  molars 
were  favorable. 


Ficj.  371. 

€lasps  flppliea  to  Porcelain  Ulork. 

Any  of  the  various  forms  of  clasp-attachments  may  be  successfully 
applied  to  porcelain  work  in  one  or  the  other  of  the  followmg  methods 
of  procedure. 

If  the  clasps  are  to  be  attached  to  the  base,  and  thus  become  a  part 
of  the  metal  substructure,  before  subjecting  the  piece  to  the  furnace, 
they  should  be  made  of  iridio-platinum  and  soldered  with  25  per  cent, 
platinum  solder. 

This  is  necessary  in  order  that  their  attachment  may  not  be  disturbed 
during  the  fusing  of  the  porcelain,  and  while  the  alloy  of  iridio-platinum 
is  not  very  stiff  nor  springy  after  being  annealed  by  passing  through  the 
furnace,  still  it  may  be  used,  and  will  answer  the  purpose  better  than  any 


48o 

other  alloy  which  we  have  at  present,  capable  of  withstanding  the  neces- 
sary heat.  It  will,  however,  become  harder  and  more  springy  as  it  is 
used,  though  perhaps  never  quite  as  resilient  as  clasp-metal. 

Whenever  it  may  seem  best  to  employ  the  ordinary  clasp-metal  in 
the  construction  of  clasps  for  porcelain  work,  this  may  be  done  by  making 
a  provision  for  subsequent  attachment  in  building  the  platinum  substruc- 
ture, in  a  manner  similar  to  that  advocated  in  making  gum  blocks,  and 
then  attaching  them  to  the  piece  with  i8  Ka.  solder,  after  the  baking  of 
the  porcelain.  This  may  be  done  without  danger  of  fracturing  any  part 
of  the  porcelain  if  the  case  is  properly  invested  and  then  slowly  but 
thoroughly  heated. 

In  both  of  the  preceding  methods,  if  preferable,  any  of  the  various 
other  forms  of  attachment  to  the  supporting  teeth — which  will  be  subse- 
quently considered — may  be  used  instead  of  clasps,  but,  by  whatever 
means  the  attachment  may  be  secured,  this  general  type  of  construction — 
as  applied  to  supplying  posterior  teeth  in  both  upper  and  lower  arches — 
is  unquestionably  the  most  useful  and  practicable,  wherever  it  may  be 
employed. 

CDc  Brvant  Itlctboa  of  Clasp  Jfttacbtncnt 

A  form  of  clasp-attachment  for  removable  dentures,  which  has  been 
devised  by  Dr.  Emory  A.  Bryant,  will  be  found  useful  in  many  positions 
where  one  or  more  natural  roots  may  be  utilized  for  carrying  a  gold 
crown,  and  a  variation  also  permits  of  its  application  to  dowel  crowns. 

The  advantage  claimed  for  this  method  is  rigid- 

Jldvantagcs.  ity  of  the  fixture,  which  is  held  firmly  against  the 

gum,  while  lateral  motion  is  likewise  prevented.  Un- 
like many  other  devices  its  usefulness  does  not  materially  decrease  with 
wear,  the  clasp  being  made  of  platinized  gold  and  therefore  readily  read- 
justed in  case  of  slight  loosening. 

This  form  of  clasp  is  indicated  especially  where 

Indications.  bicuspids  or  molars  are  to  be  supplied,  on  one  or  both 

sides,  and  where  there  is  at  least  one  good  bicuspid 
or  molar  root  sufficiently  strong  to  support  a  gold  crown.  Where  the  den- 
ture is  to  carry  teeth  on  both  sides  of  the  arch,  it  is  better  of  course  if 
the  Bryant  clasp  can  be  utilized  on  both  sides  of  the  mouth,  but  quite 
good  results  may  be  obtained  with  a  Bryant  clasp  on  one  side,  and  an 
ordinary  clasp  on  the  other. 

Briefly  described  this  form  of  clasp  attachment  consists  of  a  gold 
shell  crown,  to  the  sides  of  which  is  soldered  an  iridio-platinum  wire, 


48 1 


(usually  two  are  advisable),  the  crown  being  cemented  to  a  natural  root 
and  serving  as  an  abutment.  The  clasp  is  bent  around  the  crown  and 
adjusted  so  as  to  snugly  telescope  over  the  wire  or  wires,  and  then  is 
securely  affixed  to  the  denture. 

The  gold  shell  crown  having  been  made  and  ac- 
curately adjusted  to  the  root,  and  occlusion,  is  placed 
in  the  mouth,  and  with  a  sharp  instrument  a  scratch 
is  made  along  its  buccal  surface,  parallel  with  the 
long  axis  of  the  teeth  in  the  mouth  which  are  in  normal  position.  The 
crown  is  remove'd  and  this  scratch  is  slightly  accentuated  by  further 
scratching,  when  it  will  be  found  that  a  piece  of  iridio-platinum  wire,  i8 
or  19  ga.  will  rest  on  this  scratch  without  rolling  off,  the  crown  lying  on 


technique  of 
Construction. 


Fi^.372. 


Fi^.313. 


its  side,  in  a  little  gully  cut  in  the  charcoal  soldering  block.  The  wire 
should  be  cut  a  trifle  longer  than  the  crown.  (Fig.  372.)  If  the  tiniest 
speck  of  20  or  22  K.  solder  is  dropped  next  to  the  wire,  and  the  least  bit 
of  powdered  flux  sprinkled  over  the  spot,  the  wire  can  be  easily  united  to 
the  crown  without  displacing  it,  by  moving  a  brush  flame  over  the  whole 
till  the  solder  flows.  Powdered  flux  will  be  found  better  than  liquid  for 
this  step  of  the  work,  as  the  boiling  of  the  fluid  is  apt  to  displace  the 
wire,  and  it  is  quite  essential  that  the  wire  should  be  attached  exactly 
along  the  mark.  Next  a  little  whiting  and  water  is  painted  along  the 
side  of  the  wire  which  the  end  of  the  clasp  is  to  engage,  and  when  care- 
fully dried  will  prevent  solder  from  flowing  on  that  side,  the  round  sur- 
face of  the  wire  on  that  side  being  thus  preserved  for  the  clutch  of  the 
clasp.  When  the  whiting  is  dry,  solder  is  banked  up  along  the  other 
side  of  the  wire  to  form  a  surface  flush  with  the  crown.  (Fig.  373.)  Two 
methods  of  forming  the  clasp  may  now  be  followed.  Where  little  spring 
to  the  clasp  will  be  needed,  clasp  gold  28  ga.  will  be  found  easier  to 
handle,  and  after  it  is  properly  shaped  may  be  stiffened  by  flowing  solder 
over  its  surface.  In  many  cases,  however,  it  is  better  to  use  26  ga.  even 
though  it  may  be  necessary  to  make  the  extreme  ends  of  the  clasp  thinner 
by  filing,  or  by  hammering  on  an  anvil  with  a  light  hammer.  Whichever 
gauge  is  used  the  end  of  the  clasp  is  first  bent  so  as  to  fit  over  the  wire 


482 

and  then  is  made  to  follow  around  the  crown  at  least  two-thirds  of  its 
circumference;  farther  if  possible.  Then  the  clasp  is  cut  off  of  proper 
length  to  allow  for  turning  the  end  at  that  point,  which  is  to  engage  the 
second  wire.  Usually,  if  properly  made  the  clasp  will  now  hug  the  crown 
tightly,  and  the  second  wire  may  be  slipped  in  between  the  clasp  and 
crown.  This  is  likewise  cut  off  a  little  too  long.  The  clasp  is  then  re- 
moved and  lightly  coated  with  whiting  on  its  inner  surface ;  then  replaced 
on  the  crown,  and  the  second  wire  slipped  in.  This  time  it  is  set  on  the 
block  with  the  occlusal  surface  up,  and  a  speck  of  solder  is  dropped  be- 
tween the  crown  and  the  projecting  end  of  the  wire.  (Fig.  374.)  The 
brush  flame  of  the  blowpipe  will  tack  the  wire  and  crown  together  with 
little  or  no  danger  of  uniting  with  the  clasp,  which  may  then  be  re- 
moved, and  the  wire  more  firmly  soldered  as  was  the  first  one.  Fig.  375 
shows  the  crown  and  clasp  complete. 


Fiq.  315. 


The  crown  may  then  be  placed  in  the  mouth  with  clasp  in  place,  and 
the  fixture  to  which  it  is  to  be  attached  held  against  the  roof  of  the  mouth 
firmly  with  one  finger  while  an  impression  is  taken  in  plaster  of  Paris. 
The  fixture  and  the  clasp  are  put  in  proper  place  in  the  impression,  but 
the  crown  itself  is  omitted.  A  model  is  poured  with  a  good  investment 
compound,  and  the  clasp  united  to  the  fixture  either  direct,  or  by  a  con- 
necting bar,  according  to  the  exigencies.  Where  such  abutment  can  be 
arranged  on  both  sides  of  the  mouth  it  becomes  essential  to  observe  that 
the  telescoping  wires  are  all  parallel  with  one  another.  This  may  be  ac- 
complished by  making  a  model  from  an  impression  taken  with  both  abut- 
ment crowns  in  the  mouth  and  then,  by  utilizing  any  of  the  many  paral- 
lelling devices  the  scratches  on  the  buccal  surfaces  of  the  two  abutment 
crowns  may  be  made  parallel.  Those  on  the  lingual  surfaces  usually  are 
made  right  by  the  clasp  directing  them  to  proper  place.  In  cases  where 
the  teeth  are  badly  tipped  it  may  become  necessary  to  reverse  the  order 
of  the  work ;  that  is  the  wires  may  be  placed  on  the  lingual  surfaces 
first  in  which  case  of  course  the  paralleling  device  is  used  for  making  the 
marks  on  these  surfaces. 


483 

Where  it  is  desirable  to  arrange  for  an  occlusal  rest  it  may  be  ac- 
complished in  several  ways.  If  the  cusps  of  the  crown  be  made  solid,  a 
square  cavity  may  be  cut  therein  and  a  lip  of  the  clasp  turned  over  to  drop 
into  this  box.  Such  a  lip  should  be  reinforced  with  a  piece  of  iridio- 
platinum  wire  and  solder  (Fig.  376).  Figures  t;j'j  and  378  show  a  den- 
ture with  this  style  of  clasp. 


FIcj.  376. 


Ficj.  377. 


Fif  378. 


Ficf.  379. 


F/cj.  380. 


Ficf.  381. 


Dr.  Ottolengui,  who  has  used  the  Bryant  Clasps  extensively,  espe- 
cially in  the  construction  of  cleft  palate  carrying-plates,  prefers  either 
of  the  following  methods.  Sometimes  he  runs  a  piece  of  soft  platinum 
wire  along  the  surface  of  the  shell  crown  close  to  the  gum,  attaching  and 
stitfening  the  same  with  solder,  and  then  the  lower  edge  of  the  clasp  is 
beveled  to  drop  into  the  groove  made  by  the  upper  edge  of  this  wire.  (Fig. 
379.)     In  other  cases,  where  the  edge  of  the  clasp  will  not  irritate  the 


484 

tongue  or  cheek  he  cuts  the  end  of  the  telescope  wires  a  Httle  shorter  than 
usual,  squares  them  and  then  by  soldering  a  tiny  piece  of  clasp  gold  over 
the  top  of  the  clasp  where  it  is  bent  to  engage  the  wires,  thus  forms  a 
boxing  which,  resting  against  the  top  of  the  telescoping  wire,  prevents  the 
clasp  from  going  further  down.     (Fig.  380.) 

Where  a  cuspid  or  first  bicuspid  is  to  be  utilized  as  an  abutment  the 
display  of  gold  may  be  avoided  by  slightly  varying  the  method.  A 
dowel  crown  may  be  used,  and  grooves  cut  in  the  gold  along  the  mesial 
and  distal  sides,  and  the  ends  of  the  clasp  are  then  turned  in  so  as  to 
plav  in  these  grooves ;  this  is  somewhat  similar  to  the  arrangement  in  a 
staple  crown,  except  that  the  fixture  is  removable.  (Fig.  381.)  Where 
an  all  porcelain  crown  is  desired,  the  construction  should  include  platinum 
sides,  with  the  grooves  already  made,  prior  to  adding  the  porcelain  body. 

Special  mctbods. 

With  the  hope  of  improving  upon  the  various  forms  of  clasps,  and 
of  obtaining  a  means  of  fixation  which  would  possibly  be  less  injurious  to 
the  supporting  teeth,  and  more  secure  and  permanent,  any  number  of 
special  methods  have  been  designed. 

While  many  of  these,  among  which  may  be  mentioned  a  few  such 
as  those  of  Starr,  Winder,  Parr,  Richmond,  Curtis,  Alexander,  Rhein, 
etc.,  have  served  their  purpose  by  at  least  aiding  in  the  evolution  of  more 
practicable  procedures,  most  of  them  have  proven  to  be  either  too  intri- 
cate, or  too  limited  in  their  range  of  application,  and  have,  therefore,  been 
more  or  less  abandoned. 

For  this  reason  no  effort  to  describe  any  of  them  will  be  made, 
and  hence  only  those  which  are  used  at  the  present  time,  and  which  are 
regarded  as  possessing  some  features  of  merit,  some  range  of  application, 
and  some  degree  of  usefulness,  will  be  presented. 

Pccso's  metftoas. 

Among  these  the  ])ractical  and  ingenious  methods  of  attachment  ex- 
tensively used  by  Dr.  F.  A.  Peeso  of  Philadelphia,  are  particularly  useful. 
These  embrace  three  styles  of  attachments  and  an  interlocking  rest,  and 
when  selected  and  used  judiciously  cover  a  wide  range. 

Cube  ana  ''Split  Post"  Jlttacbment, 

As  applied  to  obtaining  a  removable  anchorage  adapted  to  the  roots 
of  teeth  the  type  of  attachment  designated  as  the  "tube  and  split-post" 


485 

orown  is  prohnhly  the  most  useful.  This  involves  the  construction  of  a 
telescoping  dowel  crown,  part  of  which  is  permanently  fixed  to  the  sup- 
porting root,  while  the  crown  portion  telescopes  into  and  over  it,  and  is 
removable. 

While    this    form    of    attachment    is    applicable 
Indications.  mainly  to  the  anterior  teeth,  where  a  dowel  crown 

would  usually  be  indicated,  the  same  principle  may 
also  be  used  upon  the  bicuspids,  or  any  of  the  anterior  teeth  provided  their 
size  is  favorable;  but  as  considetable  sacrificing  of  tooth  structure  is  de- 
manded it  is  more  particularly  applicable  to  the  roots  of  upper  cuspids 
and  sometimes  bicuspids  and  cenlral  incisors,  or  to  those  which  are  large 
enough  to  admit  of  the  necessary  preparation. 

Cccbnique  of  Construction. 

The  technique  of  construction  involves  the  preparation  of  the  root 
in  the  usual  manner  as  for  dowel  crowns  with  a  band,  after  which  the 
cap,  which  is  to  be  permanently  anchored  thereto,  should  be  constructed 
as  follows. 

A  band  of  about  30  gauge  gold  is  fitted  to  the 
Cap  and  Cube.  root,  and  carefully  festooned  to  follow  the  cervical 
margin  of  the  gum,  after  which  it  is  removed  and 
the  end  of  the  root  is  then  cut  down  to  a  point  just  below  the  gum  on 
the  labial  or  buccal  side,  but  leaving  it  about  one-sixteenth  of  an  inch 
above  the  gum  margin  on  the  lingual  side.  The  band  is  now  placed  in 
position  and  marked  around  the  inside,  close  to  the  edge  of  the  root,  with 
a  sharp  instrument.  The  canal  is  then  enlarged  to  the  size  of  the  tube 
which  is  to  be  used,  and  the  latter  should  be  made  of  coin  or  22  K.  gold, 
or  of  platinum,  about  34  ga.  If  a  gold  bridge  is  to  be  made,  the  bur  or 
reamer  should  be  leaned  slightly  toward  the  lingual  side,  thus  sloping 
the  enlarged  canal  in  that  direction,  so  that  when  the  tube  passes  through 
the  floor  there  will  be  ample  room  on  the  labial  or  buccal  side  for  the 
facing.  If  there  is  sufficient  space,  however,  to  admit  of  using  a  porce- 
lain bridge,  this  is  unnecessary.  The  tube,  after  soldering  the  seam,  and 
closing  the  apical  end  with  a  small  piece  of  plate,  is  then  rounded  on  this 
end  and  fitted  to  the  canal,  and  a  plaster  impression,  just  large  enough  to 
sustain  the  relation  of  the  band  and  tube,  is  taken. 

A  small  model  is  then  made,  the  inside  of  the  band  and  the  outside 
of  the  tube  having  first  been  given  a  very  thin  coating  of  wax  to  facilitate 
their  removal  therefrom.  The  band  is  now  cut  off  to  the  line  indicated  by 
the  scratching,  and  then  trimmed  flush  with  the  end  of  the  root,  filed  so 
that  it  is  perfectly  flat,  and  a  floor  of  28  gauge  gold  soldered  to  it.     A 


486 

hole  is  next  made  in  the  floor  and  the  tube  waxed  and  soldered  the  same 
as  the  dowel  would  be  in  the  ordinary  cap,  after  which  the  open  surplus 
end  extending  above  the  floor  is  cut  off  and  the  cap  finished  and  polished. 
(Fig.  382.) 

Crown  a«d  *$pm-Po$f" 

The  removable  part  of  the  attachment  is  made  as  follows :  The 
"post,"  of  lialf-round  iridio-platinum,  or  platinized  gold  wire,  is  bent 
double  upon  itself,  the  ends  just  caught  with  a  little  pure  or  coin  gold^ 


**»^ 


Fiq.3  82. 


and  then  filed  or  turned  to  exactly  fit  the  tube  in  the  cap.  (Fig.  383-A.) 
A  floor  of  28  gauge  gold,  or  of  iridio-platinum,  if  the  piece  is  to  be  of 
porcelain,  is  then  drilled  so  that  the  "post"  will  fit  tightly,  and  waxed  in 
place,  removed,  invested  and  soldered.  (Fig.  383-B.)  After  cleaning 
in  acid,  it  is  replaced  on  the  lower  cap,  trimmed  even  with  the  sides  all 
around  and  a  half  band  of  28  gauge  gold  or  iridio-platinum  fitted  to  the 
lingual  side,  reaching  only  to  the  gum  line,  and  toward  the  buccal  side  to 
a  point  about  where  the  facing  will  reach,  when  it  is  waxed,  removed  and 
soldered.  (Fig.  383-C.)  The  inner  caj)  is  then  placed  on  the  root  and, 
with  the  other  attachment  also  in  ])lace,  the  bite  and  impression  shpuld  be 
taken,  the  facings  selected  and  the  bridge  then  completed  in  the  usual 
manner. 


48; 
molar  JItMcbtiicnts. 

As  applied  to  molar  teeth  two  forms  of  attachment  are  employed,  one 
involving"  a  combination  of  a  telescoping  gold  crown  and  a  tube  and  "split- 
post,"  and  the  other  an  inlay  in  conjunction  with  the  same  means  of  an- 
chorage. 

Cckscoping  Crown  and  '*  Split-Post. 

In  the  construction  of  the  style  of  attachment  which  involves  a  gold 
telescope  crown  and  a  "split-post,"  the  tooth  is  devitalized  and  prepared  as 
for  a  full  gold  crown,  the  occlusal  surface  being  cut  short  enough  to  allow 
for  good  thick  cusps.  A  band  is  then  made  so  that  its  sides  are  exactly 
parallel,  or  very  slightly  larger  at  the  neck,  and  fitted  to  conform  closely 
to  the  tooth,  passing  about  one-sixteenth  of  an  inch  below  the  gum,  and 


Fi^.  384. 

then  marked  around  the  inside  even  with  the  top  or  occlusal  end  of  the 
root.  A  tube  of  suitable  size  is  used,  resting  it  on  the  floor  of  the  pulp 
chamber,  or  if  this  is  very  shallow  one  of  the  canals  may  be  enlarged  for 
a  little  distance,  and  the  tube  adjusted  in  place  so  that  it  is  exactly  par- 
allel with  the  sides  of  the  band.  (Fig.  384- A.)  An  impression  is  now 
taken  to  preserve  their  proper  relation,  the  hand  and  tube  waxed  in  the 
same  manner  as  described  in  the  former  attachment,  and  the  model  made 
from  hard  plaster.  After  it  has  been  separated,  the  band  and  tube  are 
heated  slightly  and  removed.  The  band  is  then  cut  oft  even  with  the 
occlusal  surface  of  the  root,  as  previously  marked  on  the  inside,  filed 
perfectly  flat  and  a  floor  of  28  ga.  gold  siccatcd,  or  soldered  to  it  with  a 
minute  quantity  of  solder,  after  which  the  tube  is  fitted  and  soldered  and 
the  cap  finished  the  same  as  in  the  case  of  the  former  method.  The  whole 
inside  of  the  band  is  now  given  a  z'cry  thin  coating  of  wax  and  then 
filled  with  fusible  metal.     The  outer  band  is  made  a  little  small  and  driven 


488 

over  the  reinforced  inner  cap  to  within  about  one-sixteenth  of  an  inch 
of  its  lower,  or  cervical,  edge,  so  that  it  will  only  reach  to  the  gum  line  and 
not  go  below  it.  (Fig.  384-B.)  It  is  then  cut  off  and  filed  flush  with  the 
inner  cap  and  the  floor  sweated  or  soldered  to  it.  Cusps  and  suitable  con- 
tour to  meet  the  requirements  of  occlusion,  contact,  and  alignment  are 
now  added  to  this,  and  the  split  pin  at  the  same  time  soldered  in  place, 
letting  it  extend  a  little  above  the  floor  so  that  it  may  be  firmly  attached 
to  the  cusps.  After  the  cusps  have  been  made  or  selected,  they  are  made 
solid  and  the  under  surface  filed  perfectly  flat  and  soldered  to  the  cap,  a 
hole  having  first  been  drilled  through  to  receive  the  head  of  the  "split- 
post."  The  contouring  of  the  sides  may  then  be  done  with  a  high  karat 
solder  and  after  it  is  finished  and  polished,  it  presents  the  appearance  of  an 
ordinary  properly  contoured  full  gold  crown.     (Fig.  384-C,) 


While  simple  telescoping  crowns  are  not  successful  as  a  rule,  this 
method  of  procedure  affords  one  of  the  best,  most  secure  and  permanent 
means  of  attachment,  and  when  completed,  both  parts  should  be  placed  in 
position  on  the  root,  together  with  the  other  attachments,  and  the  "bite" 
and  impression  taken,  after  which  the  bridge  may  be  completed  in  the 
usual  manner. 

The  other  form  of  attachment  to  molar  teeth 
Tnlay  Httacbmcnt.  involves  simply  cutting  a  cavity  and  using  an 
inlay  and  "split-post."  In  this  procedure  the  tooth 
is  devitalized  and  cut  on  the  occlusal  surface  about  one-half  the  length  of 
the  crown  and  down  on  the  mesial  side  to  allow  for  a  heavy  round  bar 
of  about  13  ga.  and  a  good  thickness  of  gold.  The  pulp  chamber  is 
filled  with  gutta-percha  and  the  cavity  shaped  as  illustrated  in  Fig.  385, 
leaving  the  sides  curved  and  non-retentive.  Pure  gold  about  34  or  35 
gauge  is  then  burnished  into  it  as  for  an  inlay,  being  careful  to  have  the 
margins  perfect.  A  hole  is  then  made  near  the  distal  end  of  the  matrix 
and  through  the  gutta-percha  to  the  floor  of  the  pulp  chamber  and  in  it 
is  placed  an  iridio-platinum  tube  large  enough  to  take  a  13  or  14  ga.  wire 
post.  Wax  is  now  packed  tightly  in  the  matrix  and  around  the  tube, 
and  it  is  then  removed  and  after  placing  a  piece  of  pure  gold  across  the 
approximal  side  so  that  it  can  be  entirely  and  evenly  filled  to  that  point, 


489 

it  is  invested  and  filled  with  coin  gold,  thus  making  a  perfect  gold  inlay 
with  a  tube  extending  through  it.  (Fig.  386-A.)  A  groove  is  now  cut 
from  the  tube  to  the  mesial  end  of  the  inlay.  The  bulk  of  the  cutting- 
can  be  quickly  done  with  a  thin,  round-edged  carborundum  wheel  (Fig. 
386-B),  and  finished  with  a  fissure  bur  of  the  same  size  as,  or  very 
slightly  larger  than,  the  inside  diameter  of  the  tube.  A  flame-shaped 
finishing  bur  can  be  used  to  round  the  corner  at  the  entrance  to  the  tube 
and  to  give  a  slight  downward  slant  to  the  mesial  end  so  that  the  bar 


%  386. 


F!q.3en. 

will  not  come  above  the  cusps  of  the  dummy.  Figure  387-A  shows  a  sec- 
tion of  the  inlay  and  tube  in  position  in  the  tooth  with  the  bar  and  "post" 
in  place.  The  latter  is  made  of  halfround  iridio-platinum  or  platinized 
gold  wire,  bent  double  and  soldered  to  within  about  a  quarter  of  an  inch 
of  the  end  and  filed  or  turned  to  exactly  fit  the  tube  and  grooves.  It  is 
then  bent  so  that  it  will  lie  in  the  groove  closely  and  the  closed  end  filed  so 
that  the  "split-post"  can  be  slightly  opened,  giving  it  a  spring  which  will 
hold  the  piece  firmly  in  place.  The  inlay  with  the  "post"  in  position  is 
then  placed  in  the  tooth  and  the  "bite"  and  impression  taken  in  plaster, 
the  inlay  coming  away  in  the  impression.  The  model  is  then  prepared  anil 
the  bridge  made,  the  bar  l)cing  soldered  firmly  into  it.  (big-  387-B.) 
When  it  is  finished,  the  sides  of  the  inlay  are  roughened  or  grooved 
slightly,  and  it  is  then  connected  with  the  bridge  and  cemented  as  though 
it  were  a  fixed  piece. 


490 

This  attachment  has  been  used  by  Dr.  Peeso  with  great  satisfac- 
tion for  a  number  of  years  in  molars  and  in  a  few  instances  in  bicuspids, 
but  in  the  latter  application  good  judgment  must  be  used,  as  a  bicuspid  is 
much  weaker  than  a  molar.  The  same  principle  in  a  modified  form,  anrl 
applied  to  gold  crozvns,  has  also  been  used  for  a  long  time  with  unvarying 
success. 

Tittcrlockind  Occlusal  Kcst 

An  interlocking  occlusal  rest  to  be  used  upon  one  end  of  a  bridge,  in 
conjunction  with  one  of  the  preceding  attachments  upon  the  other  end, 
and    which,    when    indicated,    and    particularly    when    adapted    to    molar 


^'9-  ^^^'  Fiq.  389. 


teeth,  as  illustrated  in  Fig.  388,  serves  the  purpose  nicely,  is  made  as 
follows : 

A  cavity  is  made  in  the  mesial  side  of  the  crown  of  the  molar,  ex- 
tending distally  to  about  half  the  length  of  the  occlusal  surface  (Fig. 
389-A),  and  a  hard  gold  filling  very  thoroughly  condensed  and  perfectly 
made  of  No.  60  rolled  gold,  inserted.  A  groove,  countersunk  at  the  distal 
end  far  enough  from  the  mesial  so  that  there  will  be  no  possibility  of  its 
giving  way  under  the  stress  of  mastication,  is  then  cut  in  the  filling, 
Fig'-  389-B  shows  this  in  sectional  view.  The  bite  and  impression  is 
now  taken  with  the  rest,  and  other  attachment,  in  place;  the  model  ob- 
tained, and  the  bridge  made  and  finished  as  usual.  It  is  usually  best  to 
put  an  orange  wood  stick  or  something  similar  between  the  abutments  in 
order  to  keep  the  space  from  closing  up  while  the  bridge  is  being  made, 
as  sometimes  the  teeth  will  move  very  rapidly.  The  rest  can  be  made 
of  round  iridio-platinum  or  platinized  gold  wire  of  No.  14  to  16  gauge. 

When  this  type  of  support  is  used  in  conjunction  with  a  tube  and 
"split-post"  attachment,  as  in  the  case  illustrated,  the  fixture  is  very 
strong,  the  bar  resting  in  the  gold  filling  in  the  molar  getting  the  full 
support  of  that  tooth,  and  the  hook  overcoming  the  possibility  of  the 
teeth  spreading,  while  the  "split-post"  and  half  band  crown  on  the  other 
end  holds  the  piece  rigidly  in  place.     If  it  is  to  be  a  porcelain  bridge,  a 


491 

very  thin  piece  oi  mica  snould  be  placed  between  the  halves  of  the  "split- 
post"  in  order  to  prevent  their  being  soldered  together  while  the  piece 
is  being  baked. 

In  the  hands  of  a  skilled  operator  these  methods  are  eminently  success- 
ful and  afford  opportunity  for  obtaining  most  practical  and  artistic  results, 
but  the  detail  must  be  very  carefully  executed,  els(;  the  work  will  be  a 
failure  as  a  result  of  the  extensive  weakening  of  the  supporting  teeth  ; 
or  of  faulty  adaptation,  or  of  lack  of  perfect  parallelism  between  the  parts. 

The  permanent  mounting  of  the  parts  which  are  to  be  affixed  to  the 
roots  with  cement,  should  never  be  made  until  the  case  is  completed,  and 
the  whole  fixture  should  then  be  forced  to  place  at  the  same  time  in  order 
to  insure  the  proper  adjustment, 


Patented,  Itlanufacturea,  and  Special  Jlttacbments  In 
Removable  Brid^eworK. 


CHAPTER  XXVII. 

The  Roach  Attachment.     The  Condit  Attachment.     The  Morgan  Attachment.     The 

Griswold    Attachment.      Kelly's    Method.      United    Abutments: 

Bryant's    Methods,    Fossume's    Methods. 


Patented  and  manufactured  Jlttacbments. 

Several  patented  and  manufactured  "systems"  of  attachment  for  re- 
movable bridgework  and  partial  dentures  have  been  more  or  less  generally 
used,  and  while  none  of  them  has  by  any  means  succeeded  in  entirely 
revolutionizing  the  construction  of  this  class  of  work,  some  have  been 
abandoned,  while  others  are  doubtless  practicable  and  may  often  be  even 
desirable. 

These  attachments  vary  considerably  in  design,  but  are  usually  com- 
posed of  two  parts  which  telescope  into  or  over  one  another,  one  of  which 
is  to  be  securely  attached  to  the  supporting  tooth,  and  the  other  to  the 
removable  fixture. 

The  advantages  which  are  to  be  derived  from  the 

Jldoantages,  use  of  such  forms  of  attachment  lie  in  the  facility 

with  which  anchorage  to  the  supporting  teeth  may 
be  obtained ;  in  the  more  or  less  secure  means  of  fixation  which  they 
afford;  in  the  fact  that  the  parts  are  usually  machine-made,  and,  there- 
fore, accurately  adjusted  in  their  relation  to  one  another,  and  that  they 
may  be  obtained  ready  for  immediate  use  directly  from  the  manufacturer 
or  dealer,  thus  saving  the  expenditure  of  time  and  energy  in  devising  a 
means  of  otherwise  retaining  such  pieces. 


493 

Notwithstanding  the  numerous  possible  advan- 
Di$advant(l9($.  tages.  however,  such  attachments  as  are  even  yet  used 

and  recommended  are  neither  universally  applicable, 
nor,  as  a  rule,  free  from  objectionable  features.  These  are  usually, 
first,  iiiJicrciit  zccakitcss,  which  results  in  their  soon  becoming 
broken ;  second,  a  demand  for  such  precise  and  accurate  parallelism 
when  two  are  to  be  on  a  single  piece,  as  to  require  the  use  of  a  par- 
alleling instrument,  and  the  exercise  of  a  greater  degree  of  skill  than  is 
ordinarily  possessed  by  the  average  dentist,  thus  making  their  use  too  in- 
tricate and  uncertain ;  third,  the  extent  of  space  occupied  by  the  attach- 
ment itself,  and  obtained  at  the  expense  of  the  adjustment  of  the  teeth  to 
be  supported  by  the  fixture ;  fourth,  the  possible  subsequent  loosening 
of  the  parts  in  their  inter-relation,  as  a  result  of  continued  friction  and 
stress,  which  may  soon  render  them  useless ;  fifth,  a  lack  of  provision  or 
opportunity  for  easily  overcoming  this,  or  for  tightening  the  adjustment; 
and  sixth,  the  leverage  imposed  upon  the  supporting  teeth,  which  may  be 
so  severe  as  to  result  in  their  subsequent  loosening,  or  ultimate  loss. 

Whenever  opportunity  for  minimizing  these  ob- 

TndiCiltions.  jectionable  features  seems  to  present,  and  whenever 

suitable  anchorage  teeth  remain  in  the  mouth,  and 

the  form  of  attachment  best  adapted  to  the  case  is  judiciously  selected, 

and  properly  and  skilfully  adjusted,  such  attachments  may  be  successfully 

employed. 

CDc  Koach  Jfrtacbitient. 

Although  among  the  most  recently  devised,  the  form  of  attachment 
designed  by  Dr.  F.  E.  Roach,  of  Chicago,  and  known  as  the  Roach  Attach- 
ment, is  one  of  the  strongest,  simplest  and  most  generally  applicable 
methods,  and  is  given  precedence  over  all  similar  forms,  for  the  fol- 
lowing reasons : 

First,  the  area  of  actual  contact  between  the  parts  of  the  attachment 
in  their  relation  to  each  other  is  so  small  that,  while  the  fixture  is  more 
or  less  rigidly  retained,  yet  some  degree  of  mobility  is  afforded,  and  thus 
the  leverage  or  tipping  strain  thrown  upon  the  supporting  teeth  is 
greatly  reduced. 

Second,  this  small  area  of  contact  allows  considerable  latitude  m  the 
adjustment  of  the  parts,  and  absolutely  accurate  paralleling  is,  therefore, 
not  required,  thus  simplifying  the  adjustment  and  overcoming  the  need 
of  a  paralleling  instrument. 


494 

Third,  the  attachment  possesses  a  maximum  of  strength,  and  yet,  in 
proportion  thereto,  as  compared  with  similar  forms,  it  occupies  a  mini- 
mum of  space. 

Fourth,  the  parts  may  be  used  interchangeably  on  either  the  "fixed" 
or  "removable"  part  of  the  piece,  and  are  also  equally  applicable  to  fill- 
ings or  crowns ;  or  to  porcelain,  gold  or  vulcanite  work,  thus  increasing 
the  range  of  application  and  usefulness. 

Fifth,  in  the  event  of  subsequent  loosening  they  may  be  easily  tight- 
ened, and  opportunity  for  accommodating  the  fixture  to  an  almost  un- 
limited degree  of  subsequent  settlement  is  also  afforded. 

The    Roach    attachment    comprises    two    parts 
CbC  Jlttacbnicnt.         which  may  be   described   as   follows :      Part   i    is  a 
slotted    round   tube   of   26   gauge   gold   clasp   metal 
(Fig.  390-A),  and  part  2  is  a  solid  ball  with  a  projecting  stem  for  at- 
tachment to  the  denture  (Fig.  390-B).    The  stem  has  a  shoulder  near  the 


ball  which  serves  the  dual  purpose  of  strength  and  finishing  line,  and 
the  extreme  end  of  the  stem  has  a  large  head  for  secure  anchorage  in 
vulcanite  work. 

The  ball  end  of  part  2  accurately  engages  into  part  i,  and  the  rigidity 
of  the  spring  metal  of  which  the  tube  is  made  maintains  a  continuous  ten- 
sion on  the  circumference  of  the  ball,  thus  affording  a  firm  anchorage 
for  the  denture,  }et  admitting  some  little  play  or  mobility. 

As  applied  to  vulcanite  work  having  made  the 
Jlpplication  to  abutment   pieces    in   the    form    of   either   gold   tele- 

Uulcanitc  mork.  scope,  or  open-faced,  or  of  porcelain-faced,  or  all 
porcelain  dowel  crowns,  take  the  "bite"  in  wax  and 
the  impression  in  plaster,  with  the  crowns  in  place,  removing  the  latter 
with  the  impression.  Fill  the  inside  of  crowns  with  wax,  run  model,  and 
then  remove  the  crowns  from  model,  clean  out  the  wax  from  inside  of 
them,  replace  them  on  model  and  wax  ])art  i,  to  place  on  crown.  If  a 
gold  crown  the  tube  may  be  held,  while  soldering,  with  a  pair  of  round- 
end  tweezers  as  in  Fig.  391,  but  when  a  dowel  crown  with  porcelain 


495 


facing  and  gold  back,  or  of  porcelain,  as  illustrated  in  Fig".  392,  or  a  gold 
inlay,  is  used  for  abutment  piece,  investment  will,  of  course,  be  neces- 
sary. 

After  tubes  are  soldered  on,  the  crowns  should  be  placed  on  model, 
part  2  adjusted  to  place,  and  the  teeth  waxed  up,  being  careful  to  have 
the  first  tooth  in  good  contact  with  the  abutment 
croivn.  Then  flask  the  case  so  that  crowns,  attach- 
ment and  teeth  all  come  away  together  in  one  side 
of  the  flask,  leaving  only  the  model  on  the  other 
side.  Part  2  should  now  be  removed  and  the  tube, 
part  I,  filled  with  cement  and  part  2  put  back  in 
place.  The  inside  of  the  tube  should  be  well  filled, 
and  a  thin  layer  of  the  cement  should  also  be  placed 
all  over  the  outside  and  up  to  the  shoulder  on  part  2. 


F/q,  392. 


Fiq.  391. 


This  luting  of  the  joints  is  necessary  to  prevent 
the  ingress  of  the  vulcanite. 

As     applied     to     gold     or 

Application  to  Gold      porcelain    work   the   procedure 

or  Porcelain  Ulork,      is  the  same  as  above  indicated 

except,  of  course,  that  a  metal 

die  and  counter-die  must  be  made  and  the  saddle 

swaged,   after  which  the   saddle   is   placed   on  the 

model  and  the  ball   (part  2)  adjusted  to  its  proper 

place  in  the  tube  and  in  relation  to  the  saddle,  and 

secured  to  the  latter  with  hard  wax.     The  saddle, 

with  part  2  thus  attached,  should  now  be  carefully 

removed  from  model,  invested  and  soldered.    Saddle 

and  abutment  crowns   should  then  be  adjusted  to 

position  in  the  mouth,  and  a  good  combination  "bite" 


496 

and  impression  in  wax  will  then  be  sufficient  for  the  completion  of  the  case 
in  the  usual  manner  in  either  gold  or  porcelain.  In  running  this  model, 
however,  do  not  flow  wax  in  crowns,  as  it  is  desirable  to  have  them  held 
securely  on  model. 

Where  gold  inlays  are  to  be  used  for  abutment 

Jlpplication  to  pieces  for  vulcanite  cases,  the  typical  application  of 

Gold  Inlays.  which  is  illustrated  in  Fig.  393-A,  flasking  will  oi 

necessity  vary.     In  such  cases  the  abutment  pieces 

and  attachments  will  have  to  remain  on  the  model  side  in  flask,  and  tc 


Flq.  393.  A. 


prevent  undue  shifting  of  stem  of  attachment,  it  will  be  necessary  to  care- 
fully pack  rubber  between  it  and  the  model  before  closing  the  flask.  Figure 
393-B,  shows  a  typical  type  of  construction  in  which  the  attachment  is 
made  both  to  an  inlay  in  the  cuspid,  and  to  a  gold  crown  on  the  molar. 

Tlic    following    ])rccautions    will    greatly    facili- 
Precautions.  tate  the  a])plication  of  these  attachments. 

I'irst.  If  tlie  tube  (Part  1  )  is  placed  so  that  it 
will  be  in  alignment  with  the  lingual  surface  of  the  teeth,  and  well 
down  toward  the  gum,  it  will  thus  be  entirely  out  of  the  way  in  all  cases. 


497 

Second.  In  soldering  the  tvibes  to  the  abutment  pieces  do  not  at- 
tempt to  do  so  until  you  have  the  latter  on  a  good  accurate  model,  as  they 
can  then  be  placed  in  proper  position  to  much  better  advantage.  Then 
wax  them  where  you  want  them,  and  grasp  them  with  soldering  tweezers 
as  illustrated ;  or  remove  and  invest,  as  the  case  may  be. 

Third.  In  cases  made  of  gold  with  vulcanite  attachment  it  is  usually 
a  good  plan  to  first  solder  the  attachment  to  the  saddles  and  then  take  a 
good  combination  "bite"  and  impression  in  wax,  with  the  base  and  abut- 
ment pieces  all  in  position. 


Ficj. 


393.  B. 


Fourth.  In  cases  where  the  abutment  pieces  have  already  been  ce- 
mented in  the  mouth,  part  2  should  be  put  to  place  with  a  bit  of  wax  be- 
tween stem  and  gum  and  a  plaster  impression  taken.  If  it  does  not  come 
away  with  the  impression,  remove  and  carefully  place  it  where  it  belongs 
therein,  and  then  slip  a  duplicate  tube  over  ball  and  run  up  model.  This 
supplemental  tube  should  be  about  half  an  inch  in  length  so  that  it  will 
securely  hold  part  2  in  place  on  the  model  during  the  construction  of  the 
'^ase. 

Fifth.  Should  the  head  on  the  stem  interfere  with  the  proper  ad- 
justment of  the  first  tooth  it  may  be  filed  ofif  on  that  side  without  injury. 
For  a  very  close  bite  a  "saddle-back"  tooth  placed  next  to  the  supporting 
tooth  may  be  used  to  advantage. 


498 


In  cases  where  it  would  seem  advantageous  to 
Uariations.  reverse  the  appHcation  of  the  parts,  and  anchor  the 

ball  instead  of  the  tube,  to  the  abutment  piece,  or 
even  to  the  crozvn  of  a  natural  toothy  that  may  be  done.  Indeed  the  latter 
application  which  is  illustrated  in  Fig.  394,  is  often  a  most  useful  pro- 
cedure. In  such  cases  a  hole  the  size  and  depth  of  the  stem  of  part  2  is 
drilled  into  the  tooth  with  a  drill  provided  for  this  purpose,  and  the 
surface  of  the  tooth  around  the  hole  then  faced 
off  so  that  the  shoulder  on  the  pin  will  set  flat 
against  the  tooth.  The  head  on  the  end  of  the 
stem  must,  of  course,  be  filed  off,  and 
the  stem  must  be  filed  flat  on  one  side  and 
thoroughly  roughened,  to  prevent  the  possi- 
bilitv  of  becoming  loosened  afterward,  when  / 


Fi^.  394.  p;^,  39S.. 

it  may  be  cemented  to  place.    The  tube  in  such  cases  must  then  be  secured 
to  the  denture  by  soldering  an  extension  of  wire  or  heavy  plate  to  it. 

Fig.  395  illustrates  a  not  uncommon  case  where  a  single  attach- 
ment would  answer  the  purpose,  provided  the  ridge  were  high,  and  promi- 
nent, and  the  bite  not  too  long,  and  more  extensive  cases  with  outline  of 
saddle,  or  base,  indicated,  and  in  which  this  method  of  attachment  would 
be  particularly  and  typically  useful  are  illustrated  in  Fig.  396  A  and  B. 

As  a  rule  the  permanent  mounting  of  the  abut- 
mounttng.  ment  piece  with  cement,   should  be  made  after  the 

attachment  has  been  finally  secured  to  and  becomes 
a  part  of  the  removable  piece.  They  should  then  be  mounted  simultane- 
ously and  the  removable  piece  at  once  forced  to  place  and  held  in  its 
proper  position  until  the  cement  has  become  thoroughly  hardened.  By 
this  means  the  proper  adjustment  is  insured,  and  the  same  precaution 
should  be  observed  in  all  of  the  succeeding  similar  methods. 


499 


CO 


C3> 


500 


tU  €ondlt  JlttacDitient 

Another  form  of  anchorage  which  is  designed  to  be  used  in  connec- 
tion with  some  type  of  artificial  crown  exchisively,  and  which  has  been 
more  or  less  extensively  used  for  a  number  of  years,  is  manufactured 
bv  the  Dental  Improvement  Co.  of  Mt.  Vernon,  Ohio,  and  is  known 
as  the  Condit  Attachment. 

This  attachment,  while  made  on  lines  somewhat  similar  to  the  pre- 
ceding one  in  that  the  telescopic  principle  is  involved,  has  a  much  greater 
surface  contact  between  the  "fixed"  and  "removable"  parts.  This  allows 
practically  no  play  and,  therefore,  makes  a  perfectly  vertical  position,  and 
absolute  parallelism,  essential  when  more  than  one  attachment  is  used 
on  a  single  case. 


ci 


Fi(j.391. 

While  tliis  demands  the  utmost  accuracy  in  using  the  attach- 
ment, still  the  same  is  true  of  most  methods  of  anchoring  removable  ap- 
pliances, and  hence  is  perhaps  not  always  to  be  regarded  as  a  particularly 
objectionable  feature. 

The  attachment,  which  is  illustrated  in  Fig.  397, 
Cb?  Jlttacbmcnt,  consists  of  a  gold  clasp  tube  (a)  open  at  the  side  and 
both  ends,  which  is  to  be  soldered  to  the  supporting 
crown,  and  a  telescoping  tube,  called  the  shield  (b),  which  is  open  at  one 
side  and  at  one  end.  This  has  a  round  pin  (c)  with  tapering  point  which 
passes  through  the  center  and  is  fastened  to  the  closed  end,  and  is  also 
provided  with  a  V-shaped  metal  projection  (d)  placed  on  the  side  of  the 
telescoping  tube  (b),  opposite  the  opening,  for  the  purpose  of  affording 
attachment  to  vulcanite,  but  is  not  used  in  metal  work.  As  the  pin  passes 
into  the  tube  (a)  the  latter  embraces  it  with  a  tension  proportionate  to  its 
spring,  and  rotation  is  in  turn  prevented  by  the  telescoping  tube  fitting 
closely  to  both  sides  of  the  inner  tube. 

The  attachment  is  machine-made  from  a  solid  piece  of  metal,  and 
the  parts  are  uniform  in  size,  interchangeable,  and  sufficiently  long  for 
any  length  of  "bice."     In  some  cases,  however,  it  may  be  necessary  to 


501 

shorten  them,  but  in  so  doing  the  end  of  the  pin  is  made  blunt.  This 
would  make  it  difficult  to  insert  it  in  the  tube,  hence  it  must  be  retapered, 
and  an  implement  for  this  purpose  is  provided,  as  is  also  an  instrument 
adapted  to  cleaning  out  the  attachment  after  vulcanizing  and  polishing, 
both  of  which  are  to  be  used  in  the  engine. 

Aside  from,  the  possible  danger  of  breaking  ofi  this  pin,  and  the 
extent  of  space  occupied  by  it,  this  form  of  attachment  may  be  found 
useful. 


Ficj.39Q, 


The  attachment  is   furnished  in  iridio-platinum 
Application.  as  well  as  gold,  and  is,  therefore,  applicable  to  either 

porcelain,  gold  or  vulcanite  work.  While  the  ad- 
justment of  a  single  attachment  may  be  made  with  the  eye,  in  those  cases 
in  which  two  or  more  are  used  on  the  same  piece,  it  is  absolutely 
necessary  that  they  be  placed  in  a  vertical  position,  and  parallel  with  each 
other,  and  for  this  purpose  a  very  simple  paralleling  instrument  is  used. 

When  the  crowns  which  are  to  support  the  "fixed"  part  of  the 
attachment  have  been  completed,  a  good  model  with  them  in  position 
thereon  should  be  obtained,  and  the  tube  part  of  the  fixture  then  tem- 
porarily attached  to  the  crowns  with  wax,  by  means  of  the  paralleling 
instrument,  pig.  398,  after  which  they  should  be  removed  and  soldered. 

In  metal  work,  the  base  should  be  swaged  and 
ntctal  Ulorh.  fitted  and  the  impression  then  taken  with  it  and  the 

supporting  crowns  in  position.  The  adjustment  of 
the  respective  parts  to  their  proper  position,  and  their  subsequent  attach- 
ment with  solder  may  then  be  effected  on  the  model,  after  which  the 
crowns  should  be  permanentl\-  mounted  with  cement,  and  the  removable 


502 

fixture  forced  to  place  and  allowed  to  remain  until  the  cement  has  become 
thoroughly  crystalized,  v;hen  a  combination  "bite"  and  impression  may  be 
taken  and  the  case  finished  in  the  usual  manner. 

AMien  the  case  is  to  be  made  of  vulcanite,  the 

Uukanite.  crowns  should  be  permanently  mounted  with  cement 

as  soon  as  the  tubes  have  been  properly  attached  to 

them,  and  the  removable  parts  of  the  attachment  should  then  be  placed 

in  their  respective  positions  on  the  crowns  and  the  "bite"  taken  in  wax, 


Ficj.SQQ.A, 


Ficj.  399,  B. 


and  the  impression  in  plaster.  These  parts  should  come  away  with  the 
impression  upon  removal,  and  it  should  then  be  observed  that  they  occupy 
their  proper  position  therein.  A  supplemental  tube,  which  is  provided, 
and  which  will  anchor  them  securely  to  the  model  during  the  process  of 
construction  and  vulcanization  should  now  be  placed  in  position  in  each 
attachment,  and  the  model  then  obtained,  after  which  the  "bite"  may  be 
adjusted,  and  the  case  finished  as  usual. 

A  simple  and  quite  common  application  where  but  a  single  attach- 
ment is  used  is  illustrated  in  Fig.  399-A,  while  a  more  extensive  case 
involving  the  use  of  two  attachments  is  shown  in  Fig,  399-B. 


503 

tbe  morgan  Jittacbmcnt 

Another  type  of  attachment  which  is  to  be  appUed  ui  much  the  same 
manner  as  the  precechng  one,  is  made  by  Dr.  J.  B.  Morgan  of  Davenport, 
Iowa,  and  is  known  as  the  Morgan  "system"  of  anchorage.  While  this 
form  of  attachment  is  more  simple  in  its  construction,  and  is  apparently 
much  stronger  than  the  former,  yet  the  telescoping  parts  fit  so  closely  that 
accurate  parallelism  in  their  adjustment  is  also  necessary,  and  little  or 


n 


Fiq.400. 


Fici.  <10I. 


Fiq.402. 

no  opportunity  is  afforded   for  tightening  the  parts   when  loosened  by 
friction,  or  for  accommodating  subsequent  settlement. 

The  attachment  consists  of  a  curved  and  flat- 
Jlttacbtticnt.  tened  tube.  Fig.  400-A,  into  which  a  two-armed  an- 

chor piece  closely  telescopes.  Fig.  400-B.  The 
curved  piece  (a)  is  called  the  "keeper,"  and  this  is  to  be  firmly  affixed  to 
the  supporting  abutment  piece.  The  anchor  piece  (b),  which  fits  snugly 
into  the  "keeper,"  has  a  projecting  stem  which  passes  between  the  open 
ends  thereof,  and  furnishes  a  means  of  anchorage  for  vulcanite,  or  of 
opportunity  for  attachment  to  a  metal  base  by  soldering,  and  a  cap  or 
cover-piece  which  limits  the  range  of  adjustment. 


504 

The  parts   are   made   in  both   gold   and   iridio- 

JTpplicatiOlU  platinum,  and  hence  are  applicable  to  either  vulcanite, 

gold  or  porcelain  work,  and  to  dowel  crowns  in  either 

gold  or  porcelain    (Fig.  401),   as   well   as   the   ordinary   gold  telescope 

crowns. 

As  absolute  parallelism  is  demanded,  the  modiis-operandi  incident 
to  the  application  of  these  attachments  is  practically  identical  with  that 
described  for  the  preceding  type,  and  a  paralleling  device  called  a  "jig," 


Fiq.403, 


and  supplemental  tubes  for  securely  holding  the  anchor  piece  to  the  model 
in  the  construction  of  vulcanite  work,  are  provided. 

A  case  which  will  serve  to  illustrate  the  typical  application  of  these 
attachments  is  shown  in  Fig.  402. 


Cbc  eriswold  Wtacbnient 

Among  the  several  methods  of  attachment  which  have  been  devised 
and  extensively  recommended  for  their  practicability  and  more  or  less 
universal  applicability  arc  those  introduced  and  known  to  the  profession 
as  the  "Griswold  System." 

These  embrace  three  different  types  of  anchorage,  designated  as  the 
"Spring  Studs,"  and  "U"  Springs,  which  are  shown  in  Fig.  403,  and  the 
"V"  Attachment.  While  the  two  former  have  been  practically  abandoned 
because  of  proving  entirely  inadequate  to  the  demands  of  removable 
fixtures,  and  of  being  too  intricate,  the  latter  may  be  found  more  or  less 
useful,  though  it  is  doul)tful  tliat  it  possesses  any  particular  advantages 
over  the  previously  mentioned  attachments. 


-SOS 


This  attachment  is  similar  to  the  Morgan  one, 

"U"  JKttaCbtllcnt,       and   may   be   used   in    much   the    same   manner.      It 

consists  of  a  pair  of  telescoping   "V"-shaped   3pen 

tubes  with  corrugated  sides   (Fig.  404-a),  one  of  which  is  to  be  affixed 

to  the  abutment  piece,  and  the  other  to  the  removable  part  of  the  fixture 

(Fig.  404-b). 


a 


F'lcj.  404. 


Ficj.4Q5. 


These  attachments  are  made  of  a  special  alloy 

Application,  which  it  is  claimed  will  not  lose  its  resiliency  when 

subjected   to  the   degree   of   heat  necessary  to   fuse 

22-K  solder.     Thus  their  application  is  limited  to  gold  or  vulcanite  work, 

unless  they  may  be  attached  to  porcelain  work  after  the  piece  has  been 

baked. 

For  vulcanite  work  it  is  recommended  that  the  removable  parts  first 
be  united  with  a  wire,  as  shown  in  Fig.  404-b.  after  their  proper  adjust- 
ment has  been  secured,  if  possible,  and  that  the  attachment  of  the  teeth 
thereto  then  be  made  with  vulcanite  in  the  usual  manner,  while  if  a  gold 
base  or  saddle  is  to  be  used,  the  attachment  of  the  parts  should  be  made 
to  it  instead  of  to  the  wire. 


5o6 

The  technique  incident  to  the  appHcation  is  otherwise  practically  the 
same  as  required  for  the  two  former  methods.  Fig.  405  illustrates  a  typi- 
cal case. 

HellV's  mctftod. 

Another  form  of  anchorage  for  removable  pieces  which  may  possibly 
have  some  field  of  usefulness,  has  been  devised  by  Dr.  J.  L.  Kelly  of  St. 
Paul,  MLin.    This  embraces  a  pair  of  short  telescoping  tubes  with  one  end 


closed,  which  are  machine-made,  of  iridio-platinum,  28  gauge,  and  in 
sizes  varying  to  meet  the  demands  of  the  tooth  to  which  they  are  to  be 
adjusted. 

In  the  application  of  this  method,  the  root  is  pre- 
Jlpplicatlon.  pared  as  for  an  ordinary  dowel  crown  with  a  band, 

and  the  usual  form  of  cap  is  made  of  28  gauge  plati- 
num and  fitted  thereto,  after  which  the  "bite,"  and  an  impression  in  plaster, 
is  taken  with  them  in  position.  The  caps  should  then  be  filled  with  wax  and 
the  model  obtained.  The  edge  of  the  inner  or  smaller  of  the  telescoping 
tube  should  be  filed  to  fit  the  floor  of  the  cap  and  so  as  to  sustain  a 
vertical  position  thereon  and  this  relation  made  permanent  by  sol- 
dering. 


507 

When  the  caps  are  thus  completed  they  should  be  replaced  upon  the 
model,  and  the  telescoping  part,  or  larger  tube,  fitted  and  adjusted  to 
them.  As  a  means  of  retaining  these  in  their  proper  relation  «:o  the 
caps,  and  to  each  other,  they  should  now  be  fitted  and  soldered  to  a  metal 
base,  or  wire,  and  the  case  then  completed  in  the  usual  manner.  Fig. 
406  shows  the  application  to  a  typical  case. 

The  size  of  these  telescoping  tubes,  and  the  alloy  of  which  they  are 
made,  doubtless  afl:'ord  some  degree  of  strength,  but  the  space  occupied  by 
them  is  obtained  at  the  expense  of  the  crown  of  the  natural  tooth  used 
to  support  them,  and  of  the  adjustment  of  the  artificial  teeth  to  be  sup- 
plied, and  these  features,  together  with  the  fact  that  a  vertical  position 
and  absolute  parallelism  must  prevail ;  that  they  must  become  loosened 
in  time  as  a  result  of  friction,  and  that  no  opportunity  for  subsequent 
settlement  is  afforded,  makes  the  method  one  of  limited  practicability. 


f/9.  407. 

Dunn's  method. 

A  very  simple  method  of  obtaining  anchorage  for  "removable 
bridges"  or  partial  dentures  which  may  sometimes  be  found  useful  is  ad- 
vocated by  Dr.  J.  E.  Dunn  of  Chicago. 

In  this  method  the  anchorage  of  the  piece  is  obtained  by  constructing 
a  gold  or  porcelain  crown  with  a  lingual  shoulder,  formed  by  an  ex- 
tension of  the  cusps  at  this  point,  as  illustrated  in  Fig.  407,  and  by 
then  making  the  fixture  so  that  it  will  spring  to  place  over  this  projec- 
tion, and  adapt  itself  snugly  to  the  body  of  the  crown. 

Where  the  principle  may  be  applied  to  supplying  the  lower  posterior 
teeth,  and  where  a  stiff  springy  clasp  metal  wire  such  as  has 
been  previously  recommended  for  lower  cases  may  be  used ;  or  where, 
in  similarly  favorable  cases,  a  vulcanite  base  may  be  made  thin  and 
springy,  this  method  oflfers  a  very  simple  and  practical  means  of  an- 
chorage. 

Similar  mctbods. 

A  considerable  number  of  methods  of  similar  character  have  been 
devised,  and  while  some  of  them  may  possibly  have  a  limited  range  of  ap- 
plication, and  may  still  be  used  to  an  extent,  many  are  already  obsolete, 


5o8 

and  others  are  not  included  for  the  reason  that  they  are  not  regarded 
as  possessing  such  special  merit  as  to  warrant  separate  consideration. 

Cbe  Principle  of  United  Jfbutments. 

The  application  of  bridgework  in  a  mouth  where  the  remaining 
natural  teeth  are  more  or  less  loosened,  is  always  a  problem  requiring  the 
most  careful  study.  It  is  evident  that  if  a  denture  is  to  be  supported  by 
abutments,  whether  permanently  attached,  or  removable,  more  than  nor- 
mal stress  must  be  resisted  by  these  abutments,  and  if  they  are  already 
weakened,  either  by  disease  or  the  loss  of  alveolar  support  through  reces- 
sion of  tissue,  the  utilization  of  them  becomes  a  hazardous  procedure. 
It  is  also  evident,  then,  that  if  something  more  than  a  temporary  result 
is  to  be  attained,  the  denture  must  be  constructed  with  especial  reference 
to  the  looseness  of  the  supporting  teeth. 

It  is  an  important  fact,  proven  by  repeated  experience  at  the  hands 
of  those  who  treat  pyorrheal  conditions  that  the  binding  together  of  two 
loose  teeth  often  more  than  doubles  the  stability  of  both.  This  is  partly 
due  to  the  prevention  of  movement  in  at  least  one  or  two  directions,  with 
the  result  that  the  supporting  alveolar  tissues  are  afforded  opportunity  of 
reattaching  to  the  roots.  Applying  this  clinical  fact  to  bridgework  a 
means  of  rendering  even  quite  loose  supporting  teeth  more  or  less  useful 
is  at  once  afforded. 

Bryant's  metDoas. 

Dr.  Emory  A.  Bryant  has  recommended  in  these  cases  the  use  of  a 
combination  fixture  a  part  of  which  is  permanent,  while  the  main  portion 
may  be  removable.  For  example,  a  case  might  present  where  the  molars 
and  second  bicuspids,  as  well  as  tv/o  or  more  of  the  incisors  niay  be  ab- 
sent from  the  upper  arch.  Examination  shows  that  the  remaining  first 
bicuspids  are  somewhat  loose.  The  natural  crowns  of  these  are  removed, 
the  pulps  extirpated  and  abutment  crowns  made  for  them.  Between 
these  bicuspid  abutments  a  stout  iridio-platinum  bar  is  formed  to  lie 
snugly  against  the  gum  tissue,  and  to  this  bar  are  fastened  the  substitutes 
for  the  missing  centrals.  This,  attached  to  the  bicuspid  abutment  pro- 
duces a  permanent  bridge  for  the  anterior  part  of  the  mouth.  To  the 
abutment  crowns,  are  fitted  the  Bryant  clasps  already  described,  and 
these  are  attached  to  the  removable  denture  which  is  to  bear  the  molars 
and  second  bicuspids. 

Even  where  no  teeth  are  missing  in  the  incisive  region,  however,  it  is 
often  wise  to  thus  attach  the  abutments  to  one  another. 


509 
Tossume's  mctbod. 

Dr.  F.  L.  Fossume  has  constructed  a  number  of  ingenious  dentures 
in  which  the  principle  of  uniting  the  abutments  is  followed  in  a  some- 
what different  manner.  The  advantages  are  reinforcement  of  loosened 
svipporting  teeth  and  greater  stability  of  the  piece,  all  lateral  motion  being 
avoided.  It  must  not  be  understood,  however,  that  this  style  of  fixture  is 
applicable  only  to  loose  teeth,  for,  on  the  contrary,  the  more  stable  the 
abutments  the  more  rigid  will  be  the  denture  in  use. 


Hcj.  U08. 


The  application  and  variations  of  Dr.  Fossume's 
Hpplicafion,  appliances  may  best  be  described  by  illustrating  a  few 

typical  pieces.  Fig.  408  gives  views  of  a  model,  on 
which  is  seen  the  ajiparatus  which  unites  the  supporting  teeth,  while  above 
it  is  the  removable  denture.  In  this  case  the  pulps  were  removed  from  the 
two  cuspids  and  both  bicuspids,  canals  properly  treated,  and  iridio-platinuni 
posts  accurately  fitted  to  all  the  canals.  Pure  gold  plate.  36  gauge,  was 
burnished  over  the  palatal  surfaces  of  the  cuspids, and  ihc  alroadx'  ]irepared 
posts  pressed  through  the  gold  into  the  canals,  the  ends  projecting.  Sim- 
ilarly, gold  was  burnished  into  the  cavities  in  the  bicuspids  through  which 
the  pulps  had  been  removed,  and  the  posts  pressed  through.     The  posts 


510 

were  tacked  with  hard  wax  to  the  gold  matrices  and  each  removed,  in- 
vested ^.nd  '■einforced  with  high-grade  solder.  They  were  then  re- 
stored to  position  in  the  mouth,  each  properly  shaped  and  polished, 
withdrawn  with  an  impression,  models  run,  and  for  each  side  the  cuspid 
and  bicuspid  parts  united  with  solder.  This  produced  practically  a  cast 
filling  for  each  side,  having  posts  that  entered  the  canals  of  cuspids 
and  bicuspids.  These  were  again  placed  in  position  in  the  mouth  and  a 
new  impression  taken.  On  the  resulting  cast  a  heavy  connecting  bar  of 
iridio-platinum  square  wire,  was  fitted  and  united  to  the  abutment  pieces 
as  shown  in  Fig.  408.     This  was  once  more  placed  in  the  mouth  and  a 


Ficf.  409. 


new  impression  taken,  and  from  this  final  cast  was  swaged  a  platinum 
saddle  which  accurately  fitted  over  the  bar  and  against  the  gum  tissue. 
At  each  end  a  small  clasp  of  gold  was  soldered  to  hug  the  lingual  surface 
of  the  cuspids ;  these  permit  tightening  of  the  denture.  Fig.  409  shows 
the  application  in  the  posterior  part  of  the  mouth. 


Extension  Bridges. 

Dr.  Fossume's  success  with  the  bar  uniting  two  supporting  teeth  has 
led  him  to  make  a  variation  which  is  applicable  where  there  is  an  abut- 
ment only  at  one  end.  I'^ig.  410  is  a  case  like  Fig.  409,  except  that  there 
is  no  posterior  abutments.  For  this  case  a  shell  crown  was  constructed 
for  the  bicuspid,  and  to  this  was  soldered  a  short,  sc|uarc  bar,  at  the  ex- 
tremity of  which  a  cross  bar  was  soldered  forming  a  T.  As  before,  the 
saddle  of  platinum  was  swaged  to  conform  to  the  ridge  and  to  engage  the 


511 

bar.  A  stout  clasp  to  encircle  the  gold  crown  was  soldered  to  the  saddle, 
and  also  carries  a  porcelain  facing,  which  is  made  on  the  tube  and  ''split- 
post"  plan  previously  described.  Fig.  41 1  shows  the  application  where 
the  posterior  teeth  are  missing  from  both  sides.  The  illustration  is  from 
one  of  Dr.  Fossume's  cases.  The  author  would  prefer  to  unite  the  two 
sides  with  a  lingual  wire  in  the  lowxr  jaw,  and  in  the  upper  with  a  narrow 
strip  across  the  roof  free  from  the  teeth.  The  construction  is  tne  same  as 
in  the  last  case,  except  that  here  dowel  crowns  were  made  for  the  cuspids 
and  united  with  bicuspid  shell  crowns  by  soldering.  In  all  of  Dr.  Fos- 
sume's cases  the  teeth  are  attached  with  rubber,  but  gold  or  porcelain 
may  be  utilized  as  the  operator  may  elect. 


F/cj.  mo. 


Cbc  Care  of  Dental  BridgcworR. 

The  duties  which  devolve  upon  the  operator  who  constructs  dental 
bridgework  and  who  is  interested  in  the  success  of  his  efforts,  and  in  the 
welfare  of  his  patients,  do  not  cease  upon  the  completion  and  insertion  of 
the  work,  but  also  demand  that  he  impart  to  the  patient  such  instructions 
as  to  the  care  of  the  same  as  will  promote  the  most  favorable  hygienic 
conditions  of  the  mouth  which  is  possible  under  the  circumstances. 

Those  who  are  compelled  to  wear  "Removable"  bridgework,  ?nd 
particularly  large  pieces,  should  be  advised  to  remove  and  carefully  but 
thoroughlv  cleanse  the  fixture  before  each  meal,  and  afterward,  also,  if 
possible,  over  a  basin  partially  filled  with  tepid  water,  and  with  a  suitable 
brush  and  a  good  soap ;  and  that  it  is  usually  best  to  remove  the  piece  upon 
retiring  and  place  it  in  a  glass  of  water,  or  preferably,  in  some  good 
properly  diluted  antiseptic  solution. 


512 

The  former  is  essential  as  a  means  of  removing  all  accumulated  and 
decomposing  secretions,  and  should  be  observed  more  particularly  before 
meals  than  afterward,  in  order  that  the  mouth  may  be  free  from  such 
deleterious  influences  during  the  meal.  Removal  at  night  is  equally  im- 
portant as  a  means  of  keeping  the  fixture  itself  in  a  thoroughly  hygienic 
condition,  and  of  allowing  the  tissues  of  the  mouth  to  rest,  and  to  assume 


nq.  4/1 


their  normal  state,  thereby  relieving  the  capillary   congestion  and  pro- 
moting the  health  of  the  parts. 

The  wearers  of  "Fixed"  bridgework — which  is  at  best  more  or  less 
unhygienic — should  always  be  advised  of  this  fact,  and  so  forcibly  im- 
pressed with  the  necessity  for  scrupulous  care  as  to  be  made  aware  of  its 
miportance.  They  should  furthermore  be  fully  instructed  as  to  exactly 
how   such  care  may  properly  be  given.     For  tlie   reasons  mentioned  a 


513 

thorough  cleansing  of  the  mouth,  and  of  all  surfaces  of  the  work  upon 
rising  every  morning,  and  previous  to  each  meal  whenever  possible, 
should  be  recommended,  and  the  proper  style  of  brush  and  antiseptic 
solution  should  be  prescribed. 

While  almost  any  good  mouth  preparation  will  answer  the  purpose, 
yet,  any  agent,  however  pleasant  or  potent,  will  fail  to  afiford  the  desired 
results  unless  the  patient  has  been  made  familiar  with  the  requirements, 
and  is  then  faithful  in  observing  them — and  these  fundamental  prerequi- 
sites will  always  depend  largely  upon  the  dentist  himself. 


ilpplication  of  the  €,mm  Proem  to 
Crown  and  Briddeworic 


flppllcatlon  M  m  Casting  Process  to  growmwork. 

CHAPTER  XXVIII. 


Application  of  the  Casting  process  to  the  Construction  of  Single  Crowns.    Porcelain 
Crowns:    Without   Band,  Selection  of   Crown,  Cement   Preferable  to  Solder, 
Requirements  for  an    Ideal   Tooth.   Technique,    Adaptation   of    Cap    to 
Root-End,    Selection  of    Tooth,   Adjustment  of    Dowel,   Adjustment 
of    Tooth,    Investing   and  Casting    Base,    Duplicates,    Soldering 
Instead  of   Casting,    Use  of   Ordinary  Facings,    Detachable 
Facings,   Duplicates,   Models,  Casting  against  Porcelain. 
Advantages  of  Cementation,  Gold  Crowns;  Construc- 
tion, Short  Roots,  Models. 


From  even  a  cursory  study  of  the  almost  unlimited  array  of  pro- 
cedures which  have  heretofore  constituted  the  methods  of  practice 
involved  in  the  construction  and  appHcation  of  crown  and  bridgework, 
it  will  at  once  be  observed  that,  notwithstanding  the  progress  made,  no 
one  general  or  systematic  line  of  procedure  has  ever  prevailed. 

While  the  myriad  of  individual  methods  and  so-called  "systems" 
which  have  from  time  to  time  been  introduced  and  recommended,  have 
embraced  such  varied  and  versatile  efforts  as  to  reflect  great  credit  upon 
the  ingenuity,  progressiveness  and  enthusiasm  of  the  profession,  and  while 
all  of  these  have  in  a  measure  contributed  to  the  development  of  this 
particular  specialty,  yet,  until  the  advent  of  the  casting  process  the 
methods  of  practice  were  necessarily  largely  empirical. 

From  the  very  first,  however,  the  casting  process  seemed  to  portend 
such  a  scope  of  usefulness,  and  such  an  unlimited  range  of  application 
to  this,  as  well  as  to  every  other  phase  of  prosthetic  dentistry,  as  to  ulti- 
mately revolutionize  all  former  procedures.  Indeed,  with  the  develop- 
ment which  has  since  been  made  along  these  lines,  and  which  is  still  pos- 
sible, most  of  them  have  already  become  more  or  less  obsolete  practices, 
and  others  will  undoubtedly  be  abandoned  from  time  to  time  as  further 
development  is  made.  In  consequence,  it  seems  safe  to  prophesy  that 
fewer  methods  will  be  used,  or  needed,  and  that  in  the  end  better  results 
will  obtain. 


5i8 

This  seems  the  logical  sequence  for  the  reason  that  accuracy  of  adap- 
tation, combined  with  a  maximum  of  inherent  strength  may  be  compared 
with,  and,  therefore,  should  be  recognized  as  the  keystone  of  the  arch  in 
the  successful  application  of  all  forms  of  crowns  and  bridges ;  and  since 
the  process  of  casting  has  made  these  essential  features  possible  to  a 
degree  never  before  achieved  in  this  work,  and  since  it  at  the  same  time 
simplifies  and  expedites  the  procedure,  it  is  unquestionably  destined  to 
become  the  universal  practice  of  the  future. 

By  insuring  the  success  and  permanency  of  the  cemented  filling, 
which,  when  the  cavity  has  been  properly  formed  and  the  filling  well 
adapted,  is  now  generally  recognized  and  conceded,  a  very  large  propor- 
tion of  teeth  which  formerly  were  restored  to  usefulness  only  by  some 
type  of  artificial  crown  may  now  be  filled  and  thus  restored  in  a  better 
and  more  permanent  manner.  Because  of  the  absence  of  the  primary 
cause  of  cervical  disturbances  so  frequently  arising  from  some  imperfec 
tion  in  the  adaptation  of  the  crown  to  the  supporting  root,  such  restora- 
tion must  be  regarded  as  a  better  procedure,  whenever  and  wherever 
applicable,  for  the  reason  that  no  matter  how  carefully  a  crown  may  be 
fitted,  no  condition  possible  to  obtain  is  quite  so  conducive  to  the  perma- 
nent comfort  and  longevity  of  the  root  as  is  the  normal. 

The  same  degree  of  accuracy  which  insures  the  success  of  the  inlay, 
however,  is  also  possible  in  the  construction  of  artificial  crowns  when 
they  are  demanded,  irrespective  of  how  well  preserved  or'  how  badly 
broken  down  the  root  may  be,  or  whether  the  crown  is  to  restore  but  a 
single  tooth,  or  to  become  part  of  a  bridge  in  addition  thereto. 

Thus  the  possible  irritating  influences  due  to  the  presence  of  an 
artificial  crown  as  formerly  constructed  are  practically  eliminated,  and 
in  addition  to  this  the  various  forms  of  separable  dowel  or  detachable 
porcelain  crowns,  instead  of  the  ordinary  thin  facings,  may  now  be  suc- 
cessfully used. 

Such  types  of  porcelain  teeth  have  always  b^tn  regarded  as  being 
the  nearest  approach  to  the  ideal,  both  in  form,  color  and  strength,  and 
in  principle  of  attachment  to  the  metal  base,  or  to  the  root  and  while, 
perhaps,  not  universally  applicable  even  now^  still  their  use,  whenever 
possible,  afifords  a  distinctive  advantage  over  ordinary  thin  facings.  At 
best,  when  compared  with  an  all-porcelain  crown,  the  latter  are  generally 
of  poor  form,  are  always  of  doubtful  color  because  of  the  necessary  use 
and  close  proximity  of  a  metal  backing  anrj  the  consequent  loss  of  trans- 
parency and  translucency,  and  are  manifestly  weaker  because  of  the  pres- 
ence of  platinum  pins  as  an  integral  ptirt  of  the  facings,  and  of  their 
rigid  attachment  to  the  supporting  struct  (ire  by  soldering. 


519 

The  presence  of  platinum  pins  in  thin  facings,  such  as  are  now  in 
general  use,  has  always  been  recognized  as  an  inherent  element  of 
weakness,  and  the  heating  and  soldering  process  has  been,  and  still  must 
be,  regarded  as  a  more  or  less  doubtful  and  sometimes  even  dangerous 
procedure.  Both  of  these  objectionable  features  may  be  overcome,  how- 
ever, by  the  use  of  detachable  or  replaceable  crowns  or  facings,  and  their 
subsequent  attachment  to  well-adapted  and  strongly  assembled  metal 
parts  by  means  of  cementation. 

As  such  an  attachment  is  equally  secure  and  manifestly  safer  than 
the  more  rigid  and  unyielding  one  resulting  from  heating  and  soldering; 
as  such  crowns  or  facings  are  certainly  stronger  than  those  in  which  the 
porcelain  is  necessarily  weakened  by  the  presence  of  platinum  pins,  and 
as  opportunity  for  replacement  in  the  event  of  accident — a  contingency 
which  is  possible  whenever  and  wherever  porcelain  is  subjected  to 
stress — is  always  present  and  favorable,  this  type  of  construction  must 
ultimately  become  more  or  less  general,  and  will  be  found  applicable  to  all 
cases  of  favorable  occlusion,  and  for  which  suitable  forms  of  porcelain 
crowns  may  be  obtained. 

With  these  combined  advantages  and  possibilities  the  construction 
of  crowns  and  bridges  may  be  accomplished  with  a  minimum  displav  of 
metal  and  a  maximum  degree  of  strength  ;  and,  therefore,  with  all  of  the 
cosmetic  and  hygienic  qualities,  and  none  of  the  doubtful  features  of 
modern  porcelain  work. 

Crown  Ulork. 

In  the  application  of  the  casting  process  to  the  construction  of  single 
crowns  tzi'o  general  types  will  be  found  to  meet  the  requirements  in  a 
very  large  percentage  of  cases. 

As  applied  to  the  restoration  of  the  ten  anterior  teeth  or  such  teeth 
as  are  within  the  range  of  vision,  or,  in  other  words,  where  the  cosmetic 
requirements  demand  the  use  of  porcelain,  the  detachable  or  separable 
dowel  crowns,  such  as  the  Davis,  White,  Justi,  etc.,  with  a  thin  well- 
adapted  cast-base,  offers  the  greatest  possible  field  of  usefulness,  and 
the  nearest  approach  to  the  ideal ;  while  as  applied  to  such  teeth  as  are 
beyond  the  range  of  vision,  or  where  the  cosmetic  requirements  are  secon- 
dary to  those  of  inherent  strength — both  in  the  crown  itself  and  in  its 
attachment  to  the  supporting  root — no  type  of  construction  will,  perhaps, 
ever  take  the  place  of  a  properly  fitted  and  well-adapted  gold  crown. 

Porcelain  Crowns. 

In  the  construction  of  porcelain  crowns  with  cast  bases,  the  require- 
ments of  root  preparation  are  practically  the  same  as  indicated  for  any 


520 

other  type  of  construction,  except,  perhaps,  that  the  labial  or  buccal  sur- 
face should  be  trimmed  a  trifle  shorter  than  the  gum  line  in  all  cases, 
as  a  means  of  insuring  the  complete  concealment  of  the  metal  base. 

A\'hen  no  band  is  to  be  used — and  one  is  seldom 
UlitbOUt  Band.  necessary   because   of  the  possibilities   of   obtaining 

absolute  accuracy  in  the  adaptation  of  the  cast  base, 
to  both  the  end  and  periphery  of  the  root — the  removal  of  the  remaining 
ledge  of  enamel  is,  of  course,  unnecessary.  When  the  root  is  cut  down  to 
the  required  point,  however,  all  of  the  advantages  of  a  band  may  be  ob- 
tained by  simply  rounding  off  the  extreme  angle  with  a  large  round  bur, 
thereby  permitting  a  thin  edge  of  the  wax  to  be  molded  over  and  around 
the  basal  end  of  the  root. 

When  the  preparation  of  the  root  has  been  completed,  unless  a 
large  selection  of  crowns  are  at  hand,  a  wax  or  modeling  compound  im- 
pression should  be  taken,  from  which  a  model  should  be  made  to  be  used 
only  for  the  purpose  of  facilitating  the  selection  of  a  crown  of  desired 
size,  form  and  color. 

The  mounting  of  a  temporary  crown  and  the  dismissal  of  the  patient 
at  this  point  will  be  found  advantageous  as  a  means  of  compressing  the 
surrounding  soft  tissue,  and  of  thus  obtaining  a  free  exposure  of  the  end 
of  the  root ;  and  also  of  affording  opportunity  for  the  subsequent  selection 
of  the  crown. 

This  procedure  will  also  be  found  advantageous  in  those  cases 
where  the  root  is  already  badly  broken  down,  as  a  result  of  accident, 
or  as  a  sequel  to  decay  and  neglect,  in  which  cases  the  casting  process 
offers  opportunities  for  obtaining  an  adaptation  heretofore  practically 
impossible. 

For  the  ten  or  twelve  anterior  teeth,  where  por- 
Sckction  celain    is   demanded    for   cosmetic    reasons,    the   all- 

ot Crown.  porcelain  replaceable  or  interchangeable  crown,  zuitJi 

cast  base,  and  with  or  without  a  band,  as  the  require- 
ments may  indicate,  may  be  successfully  used  in  a  very  large  percentage 
of  cases,  and  closely  approaches  the  ideal  form  of  artificial  substitute  for 
the  natural  tooth. 

This  type  of  crown  is  undoubtedly  the  strongest,  most  artistic,  and 
most  universally  applicaljle  substitute  at  our  command  to-day,  and  in  all 
respects  is  second  only  to  a  skilfully  adapted  "jacket"  crown.  Indeed,  for 
the  average  dentist  it  is  more  useful,  more  quickly  and  easily  made,  and, 
moreover,  it  possesses  an  advantage  over  the  latter  in  that  immediate 
replacement  in  the  event  of  mishap  is  possible. 


521 

Again,  this  type  of  porcelain  tooth  is  ideal  for  artificial  crowns, 
because  it  affords  better  form,  better  color  and  greater  strength  than  are 
possible  to  obtain  from  the  use  of  facings,  and  because  the  presence  of  an 
occlusal  surface  of  porcelain  instead  of  gold,  on  any  or  all  of  the  posterior 
teeth,  is  advantageous  not  only  for  cosmetic  and  hygienic  reasons,  but  for 
actual  masticatory  purposes  as  well. 

To  overcome  the  shortcomings  of  the  so-called  "Richmond"  crown, 
and  of  the  ordinar}^  bicuspid  and  molar  dummy  with  porcelain  facing  and 
gold  cusps,  in  bridgework,  the  advantages  of  some  form  of  interchange- 
able or  replaceable  all-porcelain  tooth,  more  closely  simulating  the  form 
and  color  of  the  natural  teeth,  were  early  recognized. 

These  advantages  have  been  so  evident  that  the  more  esthetic  ope- 
rator has  always  hoped  for  some  type  of  porcelain  tooth,  and  some 
method  of  application  which  would  eliminate  the  inherent  weakness  of 
thin  facings,  and  the  objectionable  features  incident  to  their  use. 

If    the    esthetic    and    hygienic    advantages    pos- 
r^ment  sessed  by  this  type  of  tooth,  however,  could  be  com- 

PreferablC  to  bined  with  those  of  exact  adaptation,  and  uniform 

Solder.  and  adequate  strength,  and  if  to  these  might  be  added 

the  further  advantages  of  being  cemented  to  the  basic 

structure  instead  of  soldered,  and  of  being  replaceable  and  more  or  less 

interchangeable,  it  is  evident  that  our  efforts  would  be  a  nearer  approach 

to  the  ideal. 

The  attachment  of  porcelain  teeth  or  even  facings  to  the  metal  struc- 
ture by  means  of  soldering,  or  even  of  direct  casting,  is  wrong,  in  my 
opinion.  It  is  a  wrong  principle  because  the  porcelain  is  subjected  to  a 
degree  of  heat  which  must  endanger  its  structural  integrity  and  influence 
the  preservation  of  its  color ;  because  the  tooth  or  facing  is  thus  attached 
in  a  stiff  and  rigid  manner  at  one  or  two  points  only,  and,  being  friable, 
is  more  likely  to  fracture  under  the  stress  of  mastication;  and  because, 
in  the  event  of  accident,  no  favorable  opportunity  for  repair  or  replace- 
ment is  usually  afforded. 

The  elimination  of  these  objectionable  features  must  necessarily  con- 
stitute an  improvement,  and  such  an  improvement  is  to  be  obtained  by  the 
use  of  replaceable  teeth  attached  to  the  supporting  metal  structure  only 
by  means  of  cementation. 

An  experience  of  many  years  has  proved  that  this  means  of  attach- 
ment is  reliable  in  proportion  as  the  adaptation  of  the  metal  to  the  porce- 
lain may  be  close  and  accurate,  or.  in  oilier  words,  in  proportion  as  the 
porcelain  may  be  "boxed  up,"  protected  and  supported. 


522 

It  is  stronger  when  so  attached  because  it  is  not  subjected  to  any  de- 
gree of  heat,  and  is  not  held  so  rigidly  at  a  single  point,  dtie  to  the 
adhesion  of  the  cement  over  the  entire  surface,  and  hence  it  is  less  likely 
to  become  fractured.  Furthermore,  the  color  is  never  changed;  those 
dark  blue  marginal  outlines,  due  to  the  penetration  of  saliva  between 
backing  and  facing  are  absent;  and  opportunity  and  facility  for  replace- 
ment, in  the  event  of  accident,  always  presents. 

As  previously  stated,  these  possibilities  and  ad- 

Keauircmcnts  vantages  are  to  be  adequately  obtained  only  in  some 

for  an  Ideal  form  or  type  of  tooth  which  presents  as  much  porce- 

Cootb.  lain  as  possible,  this  porcelain  not  being  weakened  by 

the  presence  of  metal  pins,  nor  by  the  provisions  for 
retention,  and  which,  therefore,  possesses  a  maximum  of  strength ;  which 
is  of  natural  form,  more  or  less  vmiversally  applicable,  and  which  zvill  re- 
quire hut  a  minimum  of  grinding  in  effecting  the  desired  and  required 
adaptation. 

This  latter  feature,  as  applied  to  the  retentive  surface,  is  essential, 
because  in  proportion  as  a  given  form  of  porcelain  tooth  will  require  but 
little  or  no  grinding  upon  this  surface  in  effecting  its  adaptation  to  the 
requirements  of  the  individual  case,  may  it  be  expected  to  be  replaceable 
or  interchangeable. 

These  combined  advantages,  I  believe,  are  to  be  obtained  in  a  form 
of  tooth  suggested  by  the  writer  and  now  known  as  the  "Goslee  Inter- 
changeable Crown  and  Bridge  Tooth." 

It  will  be  observed  that  these  teeth  as  now  made  are  of  natural  form ; 
that  they  possess  the  splendid  strength  and  color  characteristic  of  the 
Consolidated  tooth  bodies ;  that  they  are  adapted  to  single  crown  work 
where  any  form  of  metal  base  is  used,  as  well  as  to  intermediate  teeth,  or 
"dummies"  for  bridgework;  that  they  afford  a  minimum  display  of  gold, 
and  require  but  a  minimum  amount  of  grinding,  and  that  with  a  suffi- 
ciently large  variety  of  molds,  they  should  be  almost  universally  appli- 
cable; also  that  they  are  strongest  where  the  greatest  strength  is  required; 
and  that  they  offer  ample  opportunity  for  secure  retention  to  the  sup- 
porting base  or  structure. 

A  further  advantage  made  possible  by  the  use  of  replaceable  or  inter- 
changeable teeth,  which  applies  particularly  to  especially  difficult  cases,  is 
to  be  obtained  by  making  duplicates,  and  while  it  is  true  that  any  form  of 
interchangeable  tooth  is  far  less  likely  to  become  broken  from  the  stress 
of  mastication,  yet  the  making  of  duplicates  coincidcntly  with  the  initial 
construction  requires  but  little  time,  is  always  a  source  of  inestimable 
protection  to  the  particular  patient,  and  affords  unlimited  relief  and  satis- 


523 

faction  to  the  dentist.  It  is  therefore  a  safeguard  which  might  be  ob- 
served often  and  profitably  by  everyone  whose  necessarily  small  fees  do 
not  render  it  prohibitive. 

In  all  instances,  however,  whether  duplicates  are  made  or  not,  the 
color  number  and  mold  number  of  each  tooth  used  in  every  case  should 
be  recorded  on  the  card  or  ledger  sheet,  and  thus  made  a  permanent  part 
of  the  record.  Because  of  these  advantages,  and  for  these  various 
reasons,  I  firmly  believe  that  only  some  form  of  interchangeable  tooth 
should  ever  be  used  if  the  best  results  and  highest  possibilities  are  to  be 
attained  in  our  efforts. 

In   the   construction   of   all   forms   of  porcelain 
t(Cbni()U(.  crowns  with  cast  bases,  however,  and  notwithstand- 

ing the  splendid  possibilities  offered  by  the  casting 
process,  much  difficulty  has  heretofore  been  encountered  in  molding  the 
wax  to  a  close  adaptation  to  both  the  root-end,  particularly  at  the  periph- 
ery, and  the  base  of  the  crown,  and  in  holding  the  dowel  or  dowels  in  the 
proper  position  to  insure  correct  alignment. 

These  essential  features  have  usually  been  so  uncertain,  and  in  some 
instances  so  difficult  and  so  unsatisfactory,  as  to  cause  me  to  suggest  a 
technique  which,  when  used  in  connection  with  the  Goslee  tooth,  elimi- 
nates such  uncertainty,  insures  accuracy,  is  applicable  alike  to  all  cases, 
whether  a  band  is  required  or  not ;  relieves  the  patient  of  any  discomfort 
whatever,  and  which  has  proven  the  most  satisfactory  method  of  crown 
construction  I  have  ever  followed. 

In  the  various  methods  now  generally  used  and  advocated,  good,  ac- 
curate, reliable  results  are  difficult  to  obtain,  because  the  very  plasticity 
of  wax  of  any  kind  makes  it  possess  a  tendency  to  spread  when  subjected 
to  the  pressure  necessary  to  mold  it  to  a  close  adaptation.  This  tendency 
is  best  and  most  easily  overcome  by  first  adapting  38-gauge  pure  gold  or 
platinum  to  the  root-end,  which  may  be  done  either  by  swaging  or  bur- 
nishing; and  then  adjusting  the  dowel,  tacking  it  to  the  base  with  solder, 
and  subsequently  molding  the  wax  to  both  base  and  tooth,  and  casting 
directly  to  this  disc  of  gold  or  platinum.  If  this  procedure  is  carefully 
followed,  the  surface  thus  obtained  will  always  fit  more  closely  to  the 
root-end  than  would  obtain  from  the  molding  of  wax  alone,  followed  by 
the  use  of  any  investment  material  now  procurable,  and  will  require  no 
finishing  whatever  after  casting. 

The  use  of  pure  gold  is  recommended  only  because  of  the  facility 
with  which  a  close  and  accurate  adaptation  may  be  obtained  with  it. 
Platinum  of  the  same  gauge,  however,  while  a  little  more  difficult  to  adapt, 
would  answer  the  same  purpose,  and,  provided  the  same  degree  of  ac- 


524 

curacy  be  obtained,  its  use  would  afford  an  additional  advantage  in  that 
any  danger  of  fusing  or  burning  it  in  casting  to  it  would  be  entirely 
eliminated. 

Such  a  procedure  with  either  metal  also  reduces  to  a  minimum  the 
possibility  of  any  distortion  of  form  which  may  result  from  the  warpage 
or  shrinkage  of  the  gold  or  alloy  used  in  casting,  and  while  the  adaptation 
of  the  cap  may  be  made  by  burnishing,  the  very  best  results  are  to  be 
obtained  by  swaging.  The  latter  necessarily  involves  the  indirect  or  im- 
pression and  die  method,  which  is  outlined  in  systematic  order  in  the  fol- 
lowing steps : 


Fig.  412 


Fig.  414 


Fig.  413 


Fig.  415 


Fig.  416 


of  gap  to 
Root-€nd. 


First:  Prepare  the  root  in  the  usual  manner,  as 
for  any  type  of  porcelain  dowel  crown.  If  a  full  or 
partial  band  is  desired,  all  enamel  should,  of  course, 
be  removed. 

Second:    Adapt  a  base  of   thin,   pure  gold  or 
platinum  (about  38-gauge)  to  the  root-end  by  swaging. 

Third:  This  is  to  be  easily  accomplished  by  taking  an  impression  of 
the  root-end  in  modeling  compound.  Fig.  412,  investing  it  in  plaster,  Fig. 
413,  and  making  a  die  of  quick-setting  amalgam  or  cement.  An  amal- 
gam die  is  better  and  much  more  reliable,  though  it  requires  more  time. 
The  die  should  then  be  trimmed  around  the  periphery  with  a  fissure  bur 
until  the  root-end  is  freely  exposed.     Fig.  414. 


525 

Fourth:  Mount  the  die  on  the  ring  of  any  of  the  swaging  outfits, 
with  modehng  compound,  Fig.  415,  and  with  the  soft  rubber  plunger  of  a 
swaging  device  swage  a  cap  of  38-gauge  pure  gold  or  platinum  (Fig.  416). 

Fifth:   Select  a  Goslee  tooth  of  suitable  size  and 

Selection  proper  color.    The  selection  of  the  tooth  for  the  case 

Of  Cootb.  at  hand  is  best  made  by  having  a  tray  of  sample 

molds,  and  when  one  of  proper  size  and  form  has 

been  selected  simply  record  the  formula.     Thus,  for  example,  the  record 

slip  would  read,  "Upper  Right  Lateral,  Mold  51,  Color  65."     If  care  is 


Fig.  417 

exercised  in  selecting  just  exactly  the  proper  size  and  shape,  practically 
no  grinding  whatever  will  be  required. 

In  this  connection,  it  would  be  better  to  select  a  formula  just  a  trifle 
too  small  than  one  too  large.  If  the  exact  size  is  not  obtainable,  small 
additions  in  length  or  width  may  be  easily  made  in  one  bake,  using  any 
of  the  lower  fusing  bodies.  Such  additions  are  better  than  selecting  a 
tooth  which  is  too  large,  and  having  to  grind  it.  Little  or  no  grinding 
should  be  resorted  to,  as  these  teeth  are  replaceable  or  interchangeable 
only  in  proportion  as  they  may  be  used  without  grinding. 

In  the  absence  of  sample  molds,  an  impression  should  be  taken  in 
wax  or  modeling  compound,  and  a  model  made  in  plaster-of-Paris.  Fig. 
417.  The  selection  may  then  be  made  upon  this  model,  but  greater  accu- 
racy is  to  be  obtained  in  the  use  of  sample  molds  directly  in  the  mouth. 

Sixth:    When  the  tooth  has  been  selected,  the 

JfdiUStmcnt  canal  should  be  enlarged  to  receive  the  dowel  or  post. 

Of  Dowel.  This  should  be  cut  to  a  length  which  will  enter  the 

root  to  a  sufficient  depth,  and  then  engage  and  hold 

the  tooth  in  its  exact  relation  to  the  root.     In  single-rooted  teeth  a  slight 

enlarging  of  the  canal,  or  slight  bending  of  the  dowel,  or  both,  will  usually 

sustain  the  tooth  in  its  proper  alignment.     In  upper  first  bicuspids  one 

dowel  is  usually  all  that  will  be  required,  but  this  should  be  placed  in  the 

buccal  canal. 


526 

Iridio-platinum  or  clasp-metal  dowels  are  preferable  for  cast  work, 
though  the  nickel  alloys  may  be  used. 

The  dowel  should  be  round,  and  not  smaller  than  14  gauge,  though 
the  end  entering  the  canal  should  always  be  tapered  to  conform  to  the 
size  of  the  root. 

In  casting  to  clasp-metal  dowels,  care  must  be  exercised  not  to  over- 
heat the  flask  just  before  casting.  Those  who  cast  into  red  hot  flasks, 
which  is  a  mistake,  often  find  that  their  clasp-metal  dowels  are  melted 


Fig.  418  Fig.  419  Fig.  420 

and  absorbed  into  the  casting,  due  only  to  an  excessive  heating  of  the 
flask  in  melting  the  gold.  If  the  casting  may  be  made  into  a  flask  only 
moderately  warm,  however,  these  alloys  will  withstand  contact  with 
molten  22-karat  gold,  but  otherwise  iridio-platinum  pins  and  dowels  should 
be  used. 

Seventh:   When  the  dowel  and  tooth  have  been 
HdiUStmcnt  *^^^^  adjusted,  the  thin  cap  of  pure  gold  or  platinum 

Of  COOtb.  should  then  be  placed  in  position  on  the  root,  per- 

forated to  receive  the  dowel,  and  the  latter,  in  posi- 
tion in  the  crown,  forced  to  place.  The  tooth  should  then  be  removed, 
and  the  relation  between  cap  and  dowel  sustained  with  wax  or  temporary 
stopping.  Fig.  418.  The  two  should  then  be  removed  from  the  root  and 
invested  with  a  very  small  bit  of  soldering  investment  material.  Fig.  419. 
When  this  is  hard,  the  dowel  should  then  be  tacked  to  the  cap  with  a 
small  bit  of  22-karat  solder,  which  will  insure  their  permanent  relation. 
Fig.  420.  Cap  and  dowel  should  then  be  adjusted  to  position  on  the  root, 
and  finally  trimmed  and  burnished  to  the  desired  accuracy  of  adaptation. 
Eighth:  The  crown  should  then  be  ground  to  a  close  joint  along  the 
labial  or  buccal  edge,  and  other  requirements  of  adaptation  completed. 
The  base  of  the  crown  should  now  be  painted  with  glycerine  or  thin  oil, 
a  small  piece  of  soft,  clean  wax  placed  on  the  cap,  and  the  crown  then 
forced  to  its  exact  position  in  relation  to  the  cap.  The  whole  may  now 
be  removed  from  the  root,  and  the  space  between  metal  cap  and  porcelain 
teeth  filled  with  melted  casting  wax,  preferably  of  a  hard  character.    All 


527 

surplus  wax  should  now  be  nicely  trimmed  away,  and  the  porcelain  crown 
then  carefully  detached,  which  is  made  possible  by  the  lubricating  oil. 

No.  30  gold  foil  placed  in  direct  contact  with  the  porcelain  tooth  be- 
fore filling  the  space  between  it  and  the  cap  as  a  means  of  facilitating  the 
removal  of  the  crown  from  its  base,  has  been  suggested  by  Dr.  Ottolengui, 
and  may  be  used  with  good  results. 

When  the  porcelain   crown  has  been  loosened 

Tnvcsting  and         from  the  base,  but  before  it  has  been  removed,  the 

Casting  Base.         sprue-former    should    be    securely    attached    to    the 

thickest  part  of  the  wax.    The  crown  may  then  be 


Fig.  421 


Fig.  422 


Duplicates. 

should   now   be 


removed,  the  base  (Fig.  421)  invested  and  cast,  always  using  a  clean,  well 
refined  grade  of  about  22-karat  gold  for  the  casting. 

When  the  casting  has  been  made  (Fig.  422),  it 
should  be  cleaned  in  acid  and  finished.    If  duplicates 
are  to  be  made,  a  crown  of  the  same  mold  and  color 
ground  to  fit  the  cap.     The   original   should   then  be 
cemented  to  the  base  and  the  crown  polished. 

Ninth:  Whenever  it  is  absolutely  impossible  to  have  a  single  dowel 
fit  the  canal,  and  at  the  same  time  support  the  crown  in  proper  position, 
the  surplus  end  projecting  through  the  cap  should  be  cut  oft'  close  to  the 
cap,  leaving  just  a  sufficient  length  to  insure  strength.  A  separate  short 
dowel,  such  as  is  made  for  dummies  for  bridgework,  may  then  be  used  to 
support  the  crown,  and  should  be  placed  in  position  in  the  crown,  any 
unnecessary  surplus  cut  off  to  permit  of  proper  alignment,  the  porcelain 
then  lubricated,  and  the  relation  sustained  in  wax,  as  previously  indicated, 
where  a  single  dowel  is  used. 

Tenth:    In  cases  where  the  space  between  the 

cap  and  the  base  of  the  crown  is  very  small,  or  where 

it  may  not  be  convenient  or  seem  necessary  to  cast 

the  base,  good  results  may  be  obtained  with  solder. 

In  such  cases  the  porcelain  tooth  should  be  backed  up  with  38-gauge 

pure  gold  by  burnishing  or  swaging  (Fig  423)  ;  the  crown  and  backing 


Soldering  Tnstead 
of  Casting, 


528 

(Fig.  424)  then  placed  in  position  in  relation  to  the  cap,  the  porcelain 
removed,  the  case  invested,  and  the  space  between  cap  and  backing  then 
filled  with  22  or  20-karat  solder. 

This  method  is  particularly  useful  in  very  short  bicuspids,  but  where 
there  is  sufficient  space  to  permit  of  casting,  such  a  case  is  better  and 
more  uniformly  strong. 


Fig.  423 


Fig.  424 


Fig.  425 


The  entire  process  reduces  crown  construction  to  a  definite  system, 
requires  but  little  time,  is  simple,  insures  a  more  or  less  perfectly  adapted 
base,  and  one  which  is  obtained  without  the  slightest  discomfort  to  the 
patient,  which  is  not  possible  when  burnishing  directly  to  the  root-end  is 
attempted. 

For  single  crowns  a  very  narrow  lingual  and  approximal  band  is 
usually  all  that  will  be  required.  This  strengthens  the  attachment  between 
crown  and  root,  and  precludes  the  possibility  of  subsequent  fracture  of 
the  root — for  which  purposes  a  band  is  usually  used,  but  in  all  cases 
where  the  crown  is  to  be  used  as  a  bridge  abutment  a  full  band  should 
always  be  used. 

The  construction  of  a  crown  l)y  this  methorl  usually  involves  but 
three  short  sittings,  and  the  best  results  are  to  be  obtained  by  doing  all 
the  work  directly  in  the  mouth.  At  the  first  sitting  the  root  is  prepared, 
the  root  impression  taken,  the  mold  number  and  color  selected,  and  a 
temporary  crown  mounted. 

A  series  of  typical  crowns  constructed  along  these  lines  is  illustrated 
in  Fig.  425. 


529 

In  cases  where  the  use  of  a  narrow,  well-fitted 
With  Band,  band  may  seem  necessary  or  advantageous  one  may 

be  used,  and  such  a  type  of  construction  is  frequently 
indicated,  particularly  in  such  cases  as  have  previously  been  crowned 
with  this  style  of  crown,  and,  hence,  where  the  root  has  already  been 
prepared  for  a  band,  and,  therefore,  needs  similar  protection,  or  zvhere  it 
is  to  he  used  to  support  hridgework  and,  consequently,  zvhere  every 
possible  degree  of  strength  in  its  attachincnt  to  tJie  root  is  demanded. 


a 

Fig.  426 


In  such  cases  a  narrow  band  of  30  or  32  gauge,  22  k.  gold,  or  plati- 
num, soldered  Vv^ith  22  k.  or  20  k.  solder,  should  first  be  carefully  fitted 
to  the  root  and  then  so  trimmed  as  not  to  interfere  with  the  proper  adap- 
tation of  the  crown,  or  to  show  upon  the  labial  or  buccal  surface.  When 
so  fitted  the  crown  should  then  be  ground  to  place,  the  dowel  adjusted, 
and  the  wax  molded  with  the  band  in  position  on  the  root,  as  indicated. 
After  molding  the  wax,  removing  the  crown  and  wax  base,  and  again 
assembling  them  out  of  the  mouth,  the  band  should  then  be  detached 
from  the  root,  placed  in  its  proper  position  in  the  wax,  and  attached 
securely  with  a  hot  instrument.  The  surplus  wax  should  now  be  trimmed 
down  flush  and  even  with  the  band  and  crown,  and,  since  the  band  was 
made  of  a  thin  gauge  metal,  either  22  k.  gold  or  platinum,  if  any  rein- 
forcement is  wanted,  the  same  may  be  accomplished  easily  by  allowing 
a  thin  layer  of  wax  to  flow  over  the  outer  surface  of  the  band,  and  espe- 
cially over  the  joint  which  has  previously  been  made  with  solder 
(Fig.    426). 

The  sprue-wire  should  now  be  securely  attached  at  a  favorable  point., 
the  porcelain  removed,  and  the  wax  base  with  its  band  and  dowel  in  situ 
carefully  invested  and  subsequently  cast.  In  casting  it  will  be  found  that 
the  metal  cast  will  securely  attach  itself  to  both  band  and  dowel,  pro- 
vided that  both  were  clea)i,  a  precaution,  however,  which  should  always  be 
observed ;  and  the  whole  will  constitute  a  strong,  well-adapted  base. 


530 

While  the  use  of  the  various  forms  of  detach- 
U$(  Of  Ordinary         ^^^^  ^^  separable  dowel  crowns  is  undoubtedly  pro- 
Tacings.  ductive  of  the  most  artistic  achievements^  and  affords 

opportunity  for  combining  with  these  the  advantages 
of  strength  and  replacement,  the  casting  process,  however,  is  equally  ap- 
plicable to  the  ordinary  type  of  facing,  such  as  is  commonly  used  in  the 
construction  of  the  various  forms  of  porcelain-face,  metal-back,  or  so- 
called  "Richmond"  crowns.  Indeed,  in  cases  where  an  extremely  long 
overlapping  of  the  crown  upon  the  opposing  natural  teeth  demands  a  long 
and  zrry  thin  facing,  the  use  of  any  other  thicker  or  more  bulky  form  of 
porcelain  tooth  may  be  precluded. 


In  their  use,  where  the  root  has  been  propeny  prepared,  one  which 
will  meet  the  requirements  of  the  case  should  be  selected  and  ground 
to  its  proper  adjustment  in  the  mouth.  When  this  has  been  accomplished 
it  should  be  observed  that  the  pins  are  not  too  long,  nor  long  enough  to 
interfere  with  the  opposing  teeth ;  are  parallel  with  each  other,  and  at 
right  angles  with  the  facing.  A  backing  of  pure  gold  from  34  to  36 
gauge  should  then  be  perforated,  slipped  over  the  pins,  and  closely  bur- 
nished to  the  facing,  allowing  a  z'cry  slight  surplus  to  project  beyond 
the  porcelain  upon  all  surfaces  (Fig.  427  A).  The  pins  which  have  prob 
ably  been  somewhat  shortened,  should  now  be  coated  with  vaseline  or  oil, 
and  the  backing  attached  to  the  facing  by  running  a  little  melted  wax 
over  it  and  around  the  ])ins. 

The  dowel  should  now  be  fitted  and  placed  in  position  in  the  root — 
and  the  band,  also,  if  one  is  to  be  used — and  a  small  quantity  of  soft  wax 
warmed  and  molded  over  the  end  of  the  dowel  and  base  of  the  root.  The 
facing  and  its  backing  should  now  be  gently  forced  to  place  in  the  wax. 
When  the  proper  adjustment  has  been  obtained  and  secured  with  a  warm 
instrument,  the  wax  should  be  chilled,  and  the  whole  removed  and 
trimmed  up  to  the  desired  shape  and  form,  tlicn  again  tried  to  place  to 
insure  the  relation  and  adaptation  of  facing,  wax  and  dowel  to  root. 


531 

When  this  is  satisfactory  the  facing  should  be  gently  detached  from 
the  backing,  by  inserting  a  small-pointed  instrument  between  them  and 
lifted  off.  Small  pieces  of  graphite  points,  of  a  size  corresponding  with, 
or  very  slightly  larger,  than  the  pins,  which  are  made  for  vest-pocket 
pencils,  and  which  may  be  procured  at  any  stationer's,  should  now  be 
forced  through  the  holes  in  the  gold  backing  and  into  the  wax  (Fig. 
427  B),  the  sprue- wire  attached  (Fig  427  C),  and  the  case  then  invested 
and  cast. 

The  presence  of  the  thin  gold  backing,  subsequently  reinforced  by, 
and  thus  becoming  a  part  of  the  casting,  will  insure  a  smoother  surface 
presenting  toward  the  facing  than  would,  perhaps,  be  obtained  in  the 
surface  of  the  gold  which  is  cast,  because  this  is  usually  rough  in  propor- 
tion as  the  investment  material  is  porous,  or  of  coarse  texture.  The 
graphite  pins  will  preserve  the  holes  and  may  be  subsequently  removed 
therefrom  by  boiling  in  acid,  or  with  a  small  round  bur  of  the  same  size. 
When  this  has  been  done  the  facing  should  be  placed  in  position  and  the 
crown  then  finished  to  the  point  of  polishing.  The  facing  should  now  be 
removed  and  the  pins  threaded  with  a  Bryant  "tap"  designed  for  this 
purpose,  and  to  be  used  in  connection  with  replacing  broken  facings ;  or 
notched  with  a  file,  after  which  it  should  be  cemented  to  place,  using  a 
cement  which  in  color  approximates  that  of  the  facing  as  nearly  as  pos- 
sible, and  which  should  be  allowed  to  crystallize  thoroughly  before  the 
crown  is  finally  polished. 

The  same  detail  is  also  applicable  to  the  use  of 

DCtacbabk  TaclngS,     the  "Steele"  detachable  facings,  or  to  any  of  the  other 

similar  forms  of  thin  facings,  one  of  which  has  been 

suggested  by  the  author,  and  will  be  described  later  in  connection  with 

bridgework,  but  which  is  also  equally  applicable  to  single  crownwork. 

Whenever    any   replaceable    type    of    crown    or 
Duplicates.  facing  is  used,  however,  the  greatest  possible  advan- 

tages are  to  be  obtained  by  selecting  and  grinding 
duplicates  of  all  teeth  at  the  time  the  work  is  being  constructed.  When 
this  procedure  is  to  be  observed  the  crowns  or  facings  which  are  to  be 
used  at  the  time  should  first  be  ground  to  the  proper  adaptation,  and  the 
backing  for  them  then  made,  after  which  the  duplicates  should  be  ground 
to  fit  the  backing.  While  the  latter  is  not  always  a  simple  proposition, 
it  may  be  greatly  facilitated  by  painting  the  surface  of  porcelain  with  black 
oil  paint,  such  as  comes  in  small  tubes  for  artist's  use.  Articulating  or 
carbon  paper,  or  typewriter  ribbon,  may  also  be  used  for  this  purpose, 
although  the  first-mentioned  method  will  be  found  jireferable.  \Mien 
the  duplicates  are  thus  ground  to  fit  the  backings  made  for  the  originals 


532 

they  should  be  placed  in  a  small  box,  properly  labeled,  and  preserved  for 
future  use  in  case  of  accident. 

In  any  event  the  manufacturer's  formula,  or  the  mold  number  and 
color  number,  should  always  be  obtained  and  entered  upon  the  record 
as  a  means  of  enabling  the  operator  to  replace  any  particular  tooth  or  fac- 
ing at  any  time,  or  to  communicate  such  information  as  will  enable  any 
one  else  to  likewise  serve  the  patient. 

Wherever  it  may  for  any  reason  seem  advan- 
niOdClS.  tageous,  or  necessary,  to  make  models,  and  to  obtain 

the  proper  adjustment  and  molding  of  wax  upon 
them,  rather  than  in  the  mouth,  accuracy  may  be  attained  by  first  care- 
fully and  closely  adapting  a  disk  of  thin  pure  gold  or  platinum,  34  to 
38  gauge,  to  the  end  of  the  root  or  roots,  subsequently  attaching  this  to 
the  dowel  with  a  small  bit  of  22  k.  or  20  k.  solder,  and  with  this  in 
position  then  taking  the  impression  with  plaster.  After  removing  the 
impression  it  should  be  observed  that  the  disk  and  dowel  are  in  their 
correct  position  therein,  after  which  the  entire  length  of  the  latter  should 
be  covered  with  a  very  thin  coating  of  soft  wax  in  order  to  facilitate 
subsequent  removal  from  the  model.  This  may  be  done  to  good  advan- 
tage by  melting  the  wax  and  painting  it  on  with  a  small  brush.  When 
the  model  has  been  made  of  plaster,  or  a  good  investment  material,  the 
thin  disk  and  dowel  should  be  slightly  warmed,  then  gently  detached, 
removed  and  cleaned  in  the  acid  bath,  after  which  it  may  be  replaced, 
and  the  work  of  adjustment  and  molding  of  wax  done  thereon. 

A  more  or  less  accurate  model  may  also  be  made  by  first  molding 
a  small  quantity  of  wax  to  the  end  of  the  root,  with  the  dowel  in  place — • 
and  with  the  band  also  if  one  is  used — and  then  taking  the  impression 
over  this  with  plaster.  With  these  in  their  proper  place  in  the  impres- 
sion, when  the  model  is  obtained  and  the  wax  gently  and  carefully 
removed,  a  good  smooth  outline  of  the  end  of  the  root  will  usually  pre- 
sent. The  band,  if  one  has  been  made,  and  the  dowel  should  first  be 
detached  and  cleaned  in  acid,  and  the  model  then  varnished  and  oiled, 
after  which  the  proper  adjustment  of  the  parts,  and  the  molding  and  carv- 
ing of  the  wax  may  be  accomplished  with  facility  and  reasonable  accuracy. 

While  the   removal  of  the   porcelain  crown  or 

rastlna  aaainst  facing  from  the  wax  prior  to  investing  and  casting. 

Porcelain.  and  its  subsequent  attachment  to  the  metal  by  means 

of    cementation,    possesses    indisputable    advantages, 

some,  however,   may  prefer  to  include  the  porcelain  in  the  investment, 

and  cast  directly  to  it.     This  may  be  done  easily  since  such  a  procedure 

involves  only  a  question  of  heat,  and  this  demands  that  the  investment 

and  porcelain  be  heated  to  a  very  red  heat  before,  and  remain  at  this  tern- 


perature  at  the  time  of  casting.  If  this  be  carefully  done  any  of  the 
metals  or  alloys  used  in  casting,  and  favorable  to  the  requirements,  may 
be  cast  directly  to  the  porcelain,  which  will  thus  become  an  integral  part 
of  the  piece,  and  two,  or  even  more,  facings  or  crowns  may  be  included 
in  the  same  casting,  provided,  also,  that  sufficient  space  exists  between 
them  to  allow  for  a  probable  shrinkage  of  the  metal  in  cooling. 

The  only  supposed  advantage  to  be  derived  from  this  procedure, 
however,  lies  in  the  fact  that  subsequent  cementation  of  the  porcelain  to 
the  metal  is,  of  course,  unnecessary,  but  instead  of  this  being  an  advan- 
tage, it  is  regarded  as  a  disadvantage,  and  the  procedure,  at  best,  is  always 
fraught  with  uncertainty  and  danger,  especially  when  the  high  fusing 
metals  are  used. 

It  is  to  be  so  regarded  because  the  porcelain  is  thus  unnecessarily 
subjected  to  a  high  degree  of  heat,  the  intensity  of  which  always,  at 
least,  endangers  the  integrity  and  color ;  because  the  porcelain  is  attached 
in  a  more  rigid  and  unyielding  manner,  and  thus  more  likely  to  break 
under  the  stress  of  occlusion,  and  because  no  opportunity  for  replacement 
in  the  event  of  fracture  presents. 

The  elimination  of  all  of  these  possibilities  con- 
JFIdPantagCS  of  stitutes  the  very  advantages  obtained  in  the  use  of 

Cementation.  replaceable    teeth   cemented    to    place   on   the   metal 

structure.  For,  since  by  means  of  casting  it  is  now 
possible  to  obtain  an  adaptation  of  the  metal  to  the  porcelain  which  in- 
sures accuracy  and  uniform  strength ;  and  since  attachment  by  means 
of  cementation  is  conceded  to  be  reliable  in  proportion  as  the  adaptation 
is  close ;  and  as  such  attachment  is  undoubtedly  stronger ;  when  these  are 
considered  together  with  the  further  facts  that  the  porcelain  is  not 
subjected  to  any  degree  of  heat;  that  it  is  not  held  so  rigidly  and  is, 
therefore,  less  likely  to  break ;  that  its  color  is  never  changed  and  that 
replacement  is  always  possible,  the  advantages  must  necessarilv  be  re- 
garded as  unquestionable.  It  would,  therefore,  seem  that  this  method  of 
procedure  is  destined  to  be  the  more  or  less  general  practice  of  the  future. 

6oia  Crowns. 

The  application  of  the  casting  process  to  the  construction  of  gold 
shell  or  telescope  crowns  also  offers  many  advantageous  features.  By 
this  means  the  taking  of  impressions,  the  making  of  models  and  dies,  and 
the  necessity  for  swaging  and  soldering  become  unnecessary ;  all  of  the 
combined  advantages  of  the  solid-cusp^  sectional  and  seamless  methods 
are  possible,  and  may  be  accomplished  in  less  than,  or  approximately 
half  of.  the  time  previously  consumed  ;  and   better  fitting,  stronger  and 


534 

even  more  artistic  results  are  obtainable  in  proportion  as  the  operator's 
skill  and  knowledge  of  tooth  form  may  be  developed. 

In   the   construction   of  this   type   of  crown  by 

Construction.  casting  two  general  lines  of  procedure  may  be  fol- 

lowed, but  these  differ  only  in  the  width  of  band 
fitted  to  the  root,  and  the  manner  of  obtaining  form  and  contour  to  meet 
the  requirements  of  alignment,  contact  and  artistic  effect,  the  occlusion 
being  obtained  in  the  same  manner  in  both. 

Because  of  the  difficulty  of  obtaining  a  good  close  adaptation  to  the 
root  around  its  entire  circumference,  and  within  the,  free  margin  of  the 
gum,  with  so  plastic  a  substance  as  wax,  alone  and  unsupported,  the  use 


€C 


Fis.  42ii 


of  a  band  is  absolutely  necessary,  and  while  some  may  prefer  to  use  a  nar- 
row one  and  secure  the  desired  and  required  shape  and  contour  with  wax, 
rather  than  to  use  a  wide  one  and.  first  shape  it  to  comply  with  these 
requirements,  the  best  and  most  uniform  results  are  usually  to  be  obtained 
by  the  latter  method. 

In  the  procedure  which  is  regarded  as  being  the  most  simple  and 
expeditious,  and  at  the  same  time  productive  of  the  best  results,  a  band 
of  28  or  29  gauge,  22  k.  gold,  should  be  cut  in  the  usual  manner,  soldered 
with  22  or  20  k.  solder,  trimmed  to  follow  the  cervical  curvature  of  the 
gum,  and  fitted  to  the  root,  which  should  be  prepared  in  the  usual  man- 
ner, at  a  point  just  within  the  free  margin.  When  this  has  been  accom- 
plished it  should  then  be  contoured  to  conform  to  the  buccal  and  lingual 
alignment  of,  and  to  restore  contact  witli,  the  adjacent  teeth,  and  the  oc- 
clusal edge  then  trimmed  until  just  free  of  the  opposing  teeth  when 
occluded ;  and  then  filed  smooth,  after  which  it  should  be  placed  in  posi- 
tion upon  the  root  (Fig.  428  A). 

A  piece  of  hard  wax,  such  as  is  used  for  inlays,  should  now  be 
trimmed  to  such  size  as  will  fit  into  and  fill  the  entire  inside  of  the  band 
and  liberally  accommodate  the  occlusion.    When  so  trimmed  this  should 


535 

be  heated  in  water  of  the  proper  temperature,  and  then  forced  into  the 
band  against  the  end  of  the  root  and  over  and  around  the  entire  edge. 

The  patient  should  now  be  instructed  to  close  firmly  into  the  wax, 
and  then  to  indulge  in  the  various  movements  of  mastication  in  order 
that  all  such  movements  may  be  freely  accommodated  (Fig.  428  B  ). 

When  this  has  been  satisfactorily  accomplished,  a  pointed  instru- 
ment should  be  inserted  under  the  cervical  edge  of  the  band,  and  the 
whole  detached  from  the  root.  The  interior  of  the  band  should  now  be 
carefully  filled  with  the  same  investment  material  to  be  used  in  casting 


Fig.  429 


F;k.  iSO 


in  order  that  the  relation  of  the  wax  to  the  band  may  be  securely  sustained 
Vvhile  carving  i^Fig.  429  A  ).  As  soon  as  this  has  crystallized  the  surplus 
wax  should  be  trimmed  away  until  even  and  flush  with  the  band,  and  the 
occlusal  surface  then  carved  in  such  manner  as  to  preserve  several  points 
of  occlusion,  and  at  the  same  time  round  off  all  high  interlocking  points 
and  typify  the  tooth  (Fig.  429  B  ). 

In  those  cases  where  a  slight  space  exists  as  a  result  of  the  prema- 
ture loss  of  a  tooth  (Fig.  430  A  ).the  crown  may  be  found  iu  such  man- 
ner as  to  afford  an  uninterrupted  occlusal  surface  by  simply  allowing  the 
wax  to  extend  over  into  this  space  and  subsequently  carving  it  to  meet 
such  a  requirement   (Fig.     430  B  ). 

Any  additional  reinforcing  or  contouring  of  the  band  may  now  be 
made  by  flowing  wax  over  it  at  such  places,  and  as  the  joitit  has  been 
made  with  solder  which  very  probably  fuses  much  lower  tlian  the  gold,  of 
which  the  cusps  are  to  be  cast,  it  is  always  well  to  reinforce  this  with  wax 
in  order  to  preclude  the  possibility  of  its  becoming  opened  in  casting. 


556 

The  sprue-wire  should  now  be  attached  (Fig.  430  C).  and  the  crown 
then  submerged  in  water  until  the  investment  material  inside  of  the  band 
becomes  saturated  as  a  means  of  insuring  a  close  union  between  it  and  the 
fresh  matrix  to  be  used,  and  then  the  investment  for  casting  completed. 

Where  a  gold  band  is  used  in  this  manner  it  is  necessary,  of  course, 
that  a  grade  of  gold  similar  to  that  of  which  the  band  is  made  should 
be  used  for  casting  the  cusps  in  order  that  a  uniform  color  may  prevail 
throughout  the  finished  crown.  Scrap  gold,  however,  even  though  it 
contains  some  solder,  may  be  used  for  this  purpose  if  melted  and  refined 


Fig.  431 


with  saltpeter  and  borax  on  a  charcoal  block  previous  to  casting.  Indeed, 
the  presence  or  addition  of  a  small  proportion  of  solder  so  reduces  the 
fusing  point  as  to  preclude  burning  the  band,  and  increases  the  flowing 
properties  to  an  extent  which  insures  a  good  physical  union. 

In  cases  where  the  supporting  root  is  very  short 
Short  Roots.  and,  hence,  where  the  occlusal  surface  of  the  crown 

would  necessarily  need  to  be  extremely  thick  in 
order  to  fill  the  entire  space  between  the  end  of  the  root  and  the  cusps  of 
the  opposing  teeth  when  in  occlusion,  and  thus  make  the  weight  of  the 
finished  crown  objectionable,  or  the  cost  possibly  prohibitive,  either  one 
of  two  procedures  may  be  used  to  advantage. 

First,  the  root  may  be  built  up  with  amalgam  or  cement  to  approxi- 
mate the  length  of  the  band,  and  thus  diminish  the  thickness  of  the  cusps ; 
or,  second,  the  unnecessary  thickness  of  the  wax  forming  the  cusps  may 
be  reduced  to  a  minimum  by  the  use  of  the  wax  "suction  carver,"  de- 
signed by  Dr.  F.  E.  Roach,  of  Chicago  (Fig.  431  ),  This  is  a  most 
ingenious  little  contrivance  and  will  be  found  almost  indispensable  in  all 
forms  of  wax  work.  When  used  in  this  connection  the  thickness  of  the 
wax  cusps  should  be  diminished  immediately  after  removing  the  crown 


537 

from  the  mouth,  and  before  the  interior  of  the  band  is  filled  with  invest- 
ment material  as  recommended,  but  care  should  be  observed  to  preserve 
enough  of  the  shoulder  of  wax  which  is  adapted  to,  and  rests  upon,  the 
end  of  the  root  to  prevent  losing  the  very  great  advantage  of  having  the 
finished  crown  set  solidly  thereon  (Fig.  432  ). 


Fig.  432 


Indeed,  this  is  one  of  the  paramount  advantages  obtained  by  this 
method,  and  explains  the  statement  previously  made  to  the  effect  that  a 
better  fitting  crown  is  thus  possible  for  the  reason  that  crowns  so  made 
go  to  place  on  the  roots  much  as  an  inlay  does  in  a  cavity ;  it  is  impossible 
to  force  them  too  far  down^  and,  hence,  less  discomfiture  follows  after 
mounting,  and  a  minimum  quantity  of  cement  is  required  to  insure  a 
maximum  of  strength  in  the  attachment  of  crown  to  root. 


Fig.  433 


In  constructing  a  crown  where  a  narrow  band  is  used  in  preference 
to  a  wide  one,  the  cervical  end  of  the  band  must,  of  course,  be  fitted  to 
the  root  with  the  same  care  and  precision,  but  a  thinner  gauge  of  either 
22  k  gold  or  platinum  may  be  used.  A  thickness  varying  from  30  to 
32  gauge  will  answer  the  purpose  nicely,  since  it  is  used  only  to  insure 
the  correct  cervical  adaptation,  and  is  to  have  its  outer  surface  entirely 
covered  over  with  wax  and  subsequently  with  gold. 

When  properly  fitted  and  burnished  to  a  close  proximity  with  the 
axial  surfaces  of  the  root,  quite  a  large  piece  of  wax  should  be  trimmed 
to  proper  shape,  heated  and  then  molded  over  root  and  band  and  accom- 
modated to  the  occlusion.  When  this  has  been  accomplished  the  wax 
should  be  chilled  and  the  whole  removed.  If  the  band  is  not  removed 
with  the  wax  it  should  be  detached  from  the  root,  carefully  placed  in  its 
proper  position  in  the  wax,  and  sealed  with  a  hot  instrument.    The  entire 


538 

crown  may  now  be  shaped  and  carved  to  meet  the  requirements  of  aHgn- 
ment,  contact  and  occkision,  in  which  the  outer  surface  of  the  band  should 
be  completely  covered  with  the  melted  wax,  allowing  it  to  taper  down 
until  only  the  extreme  cervical  edge  is  exposed. 

A  method  quite  similar,  but  varying  in  detail  in  so  far  as  the  width 
of  band  is  concerned,  is  recommended  by  Dr.  C.  E.  Meerhoff,  of  Chicago. 
In  this  procedure  the  band  is  made  somewhat  wider,  and  in  fitting  is 
allowed  to  project  a  short  distance  beyond  or  above  the  basal  end  of  the 
root.  This  projecting  edge  is  then  slit  around  its  entire  circumference, 
and  each  flap  bent  over  until  it  rests  upon  the  end  of  the  root  (Fig. 
43.3  ^  after  which  the  wax  is  molded  and  carved  and  the  crown  com- 
pleted in  the  same  manner  (Fig.  433  B  If  any  advantage  is  possessed 
by  this  method  it  lies  mainly  in  the  fact  that  the  cap  thus  made  is  held 
more  firmly  in  its  relation  to  the  wax  than  is  a  simple  band,  and,  hence, 
any  possible  displacement  during  the  process  of  carving  is  overcome. 

While  all  of  this  carving  may  be  done  at  the 
models.  chair  and  the  crown  tried  in  from  time  to  time  until 

the  desired  artistic  results  obtain,  some  may  prefer, 
or  may  feel  that  they  work  to  better  advantage  on  models.  In  this  event 
the  usual  bite  and  impression  should  be  taken  with  the  band  in  position 
on  the  root  and  a  plaster  model  made  and  the  case  mounted  upon  the 
articulator.  When  separated  the  band  should  first  be  carefully  detached 
from  the  model,  cleaned  in  acid  and  replaced,  after  which  the  models 
should  be  coated  with  shellac  varnish,  followed  with  glycerine  or  oil  to 
prevent  the  wax  from  adhering  thereto  and  the  wax  then  molded  and 
carved  thereon. 

Since  reproductions,  however,  no  matter  how  carefully  they  may 
be  made,  are  rarely  ever  as  accurate  as  the  original,  the  use  of  models 
is  not  recommended  as  a  general  practice  and  should  be  resorted  to  only 
when  absolutely  necessary. 

Indeed,  one  of  the  beautiful  features  and  one  of  the  greatest  advan- 
tages offered  by  the  casting  process  is  the  very  fact  that  so  much  of  the 
work  which  was  formerly  confined  exclusively  to  models  may  now  be 
done  directly  in  the  mouth,  and  whenever  possible  this  undoubtedly  in- 
sures greater  accuracy  than  models  of  any  kind,  for  any  purpose. 


Jlppliufion  of  tbe  Casting  Process  to  Briddework. 

CHAPTER  XXIX. 


Attachment  to  Natural  Crowns  of  Teeth,  Attachment  to  the  Roots  of  Teeth.    Fixed 
Bridgework :    Posterior    Dummies,    Anterior    Dummies.      Inlays    as    Abutment- 
Pieces  :  Formation  of  Cavities  in  Posterior  Teeth,  Formation  of  Cavities  in 
Anterior  Teeth.     Technique :  Alaking  Wax  Inlay,  Investing,  Heating  Up 
and  Burning  Out  Wax,  Casting.    Opening  the   Bite :    Splinting  Loose 
Teeth,  Combination  of  Cast  Gold  and  Porcelain  Teeth,  Casting  to 
Surfaces  of  Metal,  Use  of  Base  Metals  and  Alloys.    Pin-Locked 
Inlays :  Porcelain  Crowns  as  Abutment-Pieces,  Gold  Crown  as 
Abutment-Pieces,    "Bite"    and    Impression,    INIodels,    Con- 
structing Posterior  Dummies,   Saddle   Formation,  Wax 
Backing,  Special  Pins,  Cast  Pins,  Sectional  Backings, 
Use    of    Diatoric    and    Vulcanite    Teeth,    Use    of 
Ordinary   Long-pin    Facings,    Gold    Dummies, 
Constructing    Anterior    Dummies :    Replac- 
able  Facings,  Replaceable  Crowns  Used 
as     Dummies,     Ordinary     Facings, 
Steele's  or  Evslin's  Replaceable 
Facings.      Typical    Cases. 


If  the  casting  process  has  revolutionized  and  simplified  the  methods 
of  procedure  in  the  construction  of  single  crowns,  it  has  also  exercised 
the  same  influences  upon  all  forms  of  dental  bridges,  where  the  field  is 
even  larger  and  where  the  possibilities  are,  therefore,  greater.  It  is  par- 
ticularly applicable  to  bridgework,  and  has  revolutionized  all  former 
methods  because  of  insuring  a  degree  of  accuracy  of  adaptation  and  of 
strength  heretofore  impossible ;  and  it  has  simplified  the  entire  field  of 
eflfort  because  these  same  possibilities  will  reduce  to  a  minimum  the  num- 
ber of  methods  formerly  used  or  now  found  to  be  necessary. 

This  is  evidenced  from  one  viewpoint,  at  least,  by  the  acknowledged 
success  and  permanency  of  the  inlay,  and  since  the  cast  filling  must  be 
regarded  as  affording  a  means  of  restoration  quite  equal  to  an  artificial 
crown,  and  in  some  respects  even  preferable,  it  must  be  classed  as  the 
ideal  type  of  anchorage  for  bridgework. 

Whenever  and  wherever  it  may  be  used  the  natural  crown  of  good 
sound  teeth,  which  heretofore  would  have  been  mutilated  to  a  greater  or 
less  extent  in  obtaining  anchorage  for  bridgework,  may  now  be  con- 
served, and  at  the  same  time  equally  good,  if  not  better  adapted,  stronger, 
and,  in  most  instances,  less  conspicuous  attachments  may  be  made  thereto. 


540 


With  such  possibiHties  and  advantages  the  inlay, 
therefore,  affords  a  more  or  less  universally  ap- 
plicable method  of  obtaining  anchorage  to  the  croiuns 
of  remaining  natural  teeth,  and,  hence,  its  use  must 
ultimately  supersede  all  of  the  various  other  methods, 
such  as  open-face  crowns,  "groove,"  or  so  called  "Carmichael,"  "plate 
and  pin"  attachments,  etc.,  which  until  now  have  been  in  common  use. 


flttacbmcnt 

to  natural  Crowtts 

of  Ceetb. 


V^ 


Fis.  iU 


Where  the  natural  crown  has  been  lost  or  sacri- 

Jlttacbmcnt  ficed,  however,  to  an  extent  which  demands  its  com- 

tO  the  Roots  of  plete   restoration,    and   where   the   attachment  must, 

Ccetb.  therefore,  be  made  to  the  root  itself,  some  form  of 

artificial  crown  must,  of  course,  be  used. 

For  this  purpose  two  general  types  of  constnictions  are  universally 

applicable — the  all-porcelain,  or  porcelain- face,  crown,  with  a  cast  base, 

for  such  teeth  as  are  within  the  range  of  vision,  or,  in  other  words,  for 

the  anterior  teeth ;  and  the  gold  crown  with  cast  cusps  for  the  posterior 

teeth  thus  embracing,  when  combined  with  the  inlay,  but  three  types  of 

attachments  which  are  generally  applicable  to,  and  which  will  meet  the 

average  and  ordinary  requirements  of  fixed  bridgework. 

Tixcd  Briddcwork. 

Since  fixed  bridgework  constitutes  simply  an  assemblage  of  attach- 
ments to  the  supporting  teeth,  or  roots,  and  of  the  intervening  "dum- 
mies" which  substitute  the  missing  teeth ;  and  since  the  three  types  of 
attachments  just  mentioned  are  universally  applicable  for  the  former 
purpose,  it  is  then  only  necessary  to  determine  what  form  or  forms  of 
"dummy"  will  best  meet  the  requirements  of  the  latter  purpose. 


541 

As  the  advantages  to  be  obtained  by  the  use  of 
POSfCflOl*  Dummies,  replaceable  teeth  are  especial!}'  valuable  in  and  par- 
ticularly essential  to  the  construction  of  fixed  bridge- 
work,  so)iie  form  of  porcelain  crozvn,  or  tootJi,  with  a  cast  backing,  un- 
doubtedly affords  the  ideal  means  of  constructing  posterior  dummies  in 
the  replacement  of  such  teeth  as  are  within  the  range  of  vision.  For  this 
purpose  the  Davis,  White,  Justi,  Twentieth  Century,  and  other  similar 
forms  of  porcelain  crowns  with  detachable  dowels,  may  be  so  ground 
as  to  be  applicable  to  a  large  proportion  of  cases,  although  a  modification 


Fig.  435 


of  form  more  especially  adapted  to  bridgework  has  been  suggested  by 
the  author,  and  is  now  made  by  the  Consolidated  Dental  Mfg.  Co.,  of 
New  York,  Fig.  434  and  the  Evslin  tooth  made  by  the  Pennsylvania 
Dental  I\Ifg.  Co.,  Fig.  435  ^Mlile  these  forms  will  be  found  well  adapted 
and  more  or  less  universally  applicable  to  this  purpose,  the  ordinary 
diatoric,  or  even  the  pin  teeth  intended  for  vulcanite  work,  may  also  be 
used  in  more  or  less  similar  manner. 

When  properly  backed  with  a  cast  backing  almost'  any  of  the  various 
forms  of  replaceable  porcelain  teeth  possess  a  maximum  of  strength,  and 
yet  afford  a  minimum  display  of  metal,  thus  making  a  stronger,  better 
and  much  more  esthetic  type  of  construction  than  the  ordinarv  thin  fac- 
ing and  gold  occlusal  surfaces  now  in  common  use.  Indeed,  the  display 
of  gold  cusps  in  the  construction  of  fixed  bridgework  has  always  been 
regarded  as  flagrantly  inartistic,  and  some  means  of  dispensing  with 
them  has  long  been  desired. 

The  actual  requirements   for  anterior  dummies 

TInteiior  Dummies.       differ  mainly  in  that  the  extent  of  absorption  in  the 

region  of  the  six  anterior  teeth  in  particular  usually 


542 

demands  a  more  or  less  thin  form  of  tooth  or  facing-.  For  this  reason  the 
separable  dowel  crowns,  if  ground  as  illustrated  in  Fig.  436,  may  be 
occasionally  utilized  wherever  the  extent  of  absorption  is  sufficient  to 
admit,  yet  they  are  not  universally  applicable,  though  all  of  the  ad- 
vantages of  a  replaceable  form  of  tooth  which  they  possess  are  equally 
desirable. 

While  the  ordinary  long-pin  flat-back  facings  may  be  used,  as  sug- 
gested in  the  construction  of  single  anterior  crowns,  or  the  Steele  and 
similar  forms  of  so-called  bridge-teeth,  or  even  simple  vulcanite  teeth. 


Fig.  436 


Fig  43 


the  author  has  suggested  a  type  of  tooth  for  this  purpose  which  seems  to 
offer  a  maximum  degree  of  strength,  the  thinness  usually  demanded  in 
application  to  the  replacement  of  the  eight  anterior  teeth,  and  all  of  the 
advantages  of  the  replaceable  form  of  tooth  combined. 

This  type  of  tooth  is  identical  in  size  and  form  with  the  ordinary 
facing,  but  instead  of  having  pins  in  it,  holes  are  placed  in  exactly  the 
same  postion  and  relation  to  the  porcelain  and  to  each  other.  These  holes 
have  a  very  slight  shoulder  or  seat  at  the  surface  of  the  porcelain  exactly 
like  the  Davis  crown,  only  smaller,  and  are  slightly  countersunk  at  the 
lower  ends.  The  shoulder  at  the  surface  of  the  porcelain  affords  accom- 
modation for  the  thin  diaphragms  on  the  pins,  which  insures  perfect 
parallelism  between  them  ;  and  the  countersink  at  the  end  of  the  holes 
affords    accommodation    for    a    slight    surplus    of    cement    in    mounting 

(Fig-  437). 

The  diaphragm  is  in  the  exact  center  of  the  pin,  and  is  about  15 
gauge  in  diameter  and  30  gauge  in  thickness,  and  the  pin  is  from  17 
to  18  gauge,  with  each  end  notched  as  a  means  of  facilitating  the  attach- 


543 

ment  of  the  pins  to  the  cast-metal  backing,  on  one  end,  and  of  the  porce- 
lain facings  to  the  other  ends,  with  cement.  They  may  be  made  of  iridio- 
platinum,  gold  and  platinum,  clasp-metal,  or  any  of  the  German  silver 
alloys. 

These  facings  are  now  in  the  hands  of  several  manufacturers  and 
will  doubtless  soon  be  procurable. 

With  these  two  general  types  for  anterior  dummies,  with  the  former 
type  for  posterior  dummies,  and  with  cast-gold  dummies  for  such  places 
in  the  posterior  part  of  the  mouth  as  present  conditions  of  absorption  and 
occlusion  which  preclude  the  use  of  any  form  of  porcelain  tooth  or  facing, 
embracing  in  all  but  three  or  four  general  types,  it  will  be  observed  that 
the  actual  requirements  in  connection  with  "dummies"  for  fixed  bridge- 
work  are  practivally  included. 

Tnlays  as  Jlbutmcnt-Pleccs. 

In  the  application  of  inlays  as  "abutment-pieces"  or  "attachments" 
for  fixed  bridgework,  in  the  formation  and  preparation  of  the  cavity, 
every  precaution  must  be  observed  to  insure  a  secure  mechanical  fixation 
of  the  inlay.  This  is  necessary  because  any  inlay  for  a  simple  restoration, 
much  less  one  which  is  to  be  utilized  as  a  support  for  bridgework,  which 
depends  entirely  upon  cement  for  its  retention,  will  usually  fail,  and 
particularly  if  it  is  to  be  subjected  to  stress  in  any  direction. 

In  addition  to  such  favorable  mechanical  formation,  at  least  one,  and 
sometimes  two,  short  pins,  made  of  from  i8  to  20  gauge  round  iridio- 
platinum  wire,  should  invariably  be  used  in  teeth  having  vital  pulps,  and 
larger  and  longer  ones  where  the  pulp  has  been  removed,  as  a  means  of 
obtaining  every  possible  degree  of  security  and  permanency  in  the 
attachment  of  the  inlay  to  the  tooth. 

When  such  pins  are  used  in  teeth  having  vital  pulps,  holes  should 
be  drilled  (using  a  bur  of  the  same  size  as  the  wire)  into  the  base  of  the 
cavity  at  a  point  which  will  be  least  likely  to  expose  the  pulp,  and  parallel 
with  the  axial  walls  of  the  cavity,  and  with  each  other,  if  more  than  one 
is  used.  They  should  extend  into  the  dentin  as  far  as  possible  without 
endangering  exposure  of  the  pulp,  and  project  beyond  the  hole  and  into 
the  body  of  the  cavity  sufficiently  to  admit  of  their  becoming  securely 
attached  to  the  wax  in  molding  it  to  the  cavity.  When  so  fitted  they 
should  then  be  threaded  with  a  "tap"  or  notched  with  a  file  to  insure 
attachment  of  gold  in  casting  and  of  cement  in  mounting  (Fig.  438  A). 

In  pulpless  teeth  one  pin  is  all  that  is  necessary,  but  this  should  be 
about  16  gauge  in  size  and  should  extend  through  the  pulp-chamber  and 
into  the  canal  to  a  slightly  greater  extent  (Fig.  438  R").  In  cases  where 
it  seems  impossible  to  drill  holes  of  such  depth  as  will  insure  adequate 


544 

strength  in  the  attachment  of  the  inlay  to  the  tooth,  without  endangering 
the  hfe  of  the  pulp,  devitalization  may  be  demanded  and  should  be  re- 
sorted to  when  any  question  of  doubt  or  uncertainty  arises. 


Fig.  438  A 


Fig.  438  B 


Fig.  439 


In  the  preparation  of  cavities  in  the  posterior 
teeth  for  inlays  which  are  to  support  bridgework, 
care  must  be  exercised  to  break  down  and  cut  away 
all  thin,  frail  walls ;  to  form  the  cavity  with  a  square, 
flat  base,  with  the  axial  margins  parallel  or  slightly 
diverging,  and  beveled  to  the  extent  of  properly  protecting  the  enamel 
rods.     Extension  for  prevention  must  also  be  observed  in  following  out 


Tormation  of 

eaoities  in  Posterior 

Cectb. 


545 

pits  and  fissures  and  particularly  in  cutting  away  the  approximal  sur- 
faces to  an  extent  which  will  afford  freely  exposed  and  self-cleansing 
margins. 

This  is  especially  necessary  upon  the  approximal  surface  adjacent  to 
the  space  where  teeth  are  missing  and  against  which  the  artificial  bridge 
tooth  is  placed.  The  requirements  of  contact  between  the  filling  and  the 
artificial  tooth,  and  of  strength  in  their  subsequent  attachment,  at  this 
point,  demands  that  the  cavity  be  sufficiently  broad  bucco-lingually  to 
afford  opportunity  for  this  and  at  the  same  time  allow  a  free  exposure 
of  the  cervical,  buccal  and  lingual  margins.  The  outlines  of  the  cavity 
and  filling  in  Fig.  439  will  illustrate  the  surface  of  the  filling  to  which 
attachment  of  the  adjacent  artificial  tooth  should  be  made,  and  the  extent 
to  which  the  margins  of  the  filling  should  be  allowed  to  remain  freely 
exposed. 

Small  stones  of  various  sizes  and  shapes  will  be  found  extremely 
useful  in  this  work,  and  when  they  may  be  used  are  much  preferable  to 
burs,  and  much  easier  for  the  patient. 

Several  typical  types  of  cavity  formation  adapted  to  inlays,  which 
are  to  be  used  as  abutments  for  bridgework  as  applied  to  the  posterior 
teeth,  are  illustrated  in  Fig.  44°- 

If  the  casting  process  had  made  possible  nothing 
Tormation  OT  more  than  the  accurate  adaptation  of  attachments  to 

0a9itie$  In  JInUrior      the  natural  crowns  of  anterior  teeth,  for  the  support 
Ccetb.  of  bridgework,  it  would  still  have  filled  a  most  im- 

portant and  useful  mission.  Prior  to  its  advent  a 
number  of  different  methods  of  obtaining  attachment  were  advocated 
and  used,  but  because  of  the  difficulty  of  securing  any  great  or  uniform 
degree  of  accuracy  in  their  adaptation,  natural  teeth  so  used  were  often 
subsequently  lost  as  a  result  of  this  deficiency. 

Now,  however,  since  the  accurate  adaptation  of  the  inlay  to  the 
cavity  is  insured,  the  success  and  permanency  of  such  attachments  re- 
solves itself  into  the  simple  question  of  the  best  type  of  cavity  formation 
to  be  applied  to  the  individual  case,  and  this,  of  course,  must  necessarily 
vary  with  the  conditions  presenting. 

In  making  attachment  to  upper  incisors,  where  the  tooth  to  be  used 
stands  free  of  adjacent  teeth  on  each  side,  as  indicated  m  Fig.  44  f,  the 
cavity  formed  should  involve  both  approximal  surfaces  and  should  extend 
across  the  incisal  end,  allowing  as  much  of  the  labial  plate  of  enamel  to 
remain  as  is  possible,  but  extending  the  approximal  margins  far  enough 
labially  to  allow  them  to  be  free  from  contact  of  adjacent  artificial  teeth 
(Fig.  44-).    In  such  cases,  when  the  pulp  is  vital,  small  pins  may  or  may 


546 

not  be  indicated,  but  it  is  always  safer  to  use  them  whenever  there  is 
any  doubt,  while  in  cases  where  the  pulp  has  been  or  must  be  devitalized, 
the  use  of  a  pin  is  almost  invariably  indicated. 

Where  the  attachment  is  to  be  made  to  a  tooth  having  an  adjacent 
natural  tooth  on  one  side  of  it  as  indicated  in  Fig.  443,  only  the  ap prox- 
imal presenting  foivard  the  space  and  the  lingual  surfaces  need  be  in- 


fig.  411 


I^ 


Fig.  448 


volved,  but  one  or  two  pins  should  invariably  be  used,  and  the  filling 
should  extend  far  enough  around  the  labial  angle  to  be  free  from  contact 
with  artificial  teeth,  and  all  margins  well  defined  (Fig,  444). 

Cavities  in  upper  cuspids  and  bicuspids  which  stand  alone,  and  where 
no  decay  is  present,  may  be  formed  as  for  the  ordinary  "groove,"  or  so- 
called  Carmichael  attachments  (Fig.  445),  while,  if  approximal  cavities 
are  present,  the  formation  may  be  made  along  the  same  lines  as  for 
incisors. 

As  applied  to  the  lower  incisors,  a  secure  attachment  may  be  made 
by  forming  the  cavity  as  outlined  in  Fig.  446,  which,  when  a  pin  is  used, 
insures  a  good  adaptation,  adequate  strength,  and  practically  no  display 
of  gold.  In  cases  where  some  little  display  of  gold  may  not  be  objection- 
able the  cavity  formation  suggested  by  Dr.  F.  E.  Roach  will  be  found 
useful  (Fig.  447).  In  this  type  of  attachment  it  will  be  observed  that  the 
use  of  a  pin  will  not  be  necessary. 


547 

Lower  cuspids  and  bicuspids  may  be  used  much  in  the  same  manner 
as  indicated  for  the  upper  teeth,  but  in  all  cases  the  cavities  must  be  so 
formed  as  to  have  definite  margins  to  which  the  inlay  may  be  closely 
finished,  and  these  margins  should  always  be  extended  to  an  area  which 
will  be  free  from  contact  with  adjacent  artificial  teeth  and  thus  rendered 
self-cleansing. 


Fig.  443 


f 


Fig.  iU 


CecDniqtie. 

When  the  cavity  has  been  properly  formed  and  all  margins  made 
well  defined  and  smooth,  the  pins,  if  any  are  used,  should  then  be  placed 
in  position  in  the  tooth,  having  a  little  bead  of  wax  melted  around  their 
previously  notched  surplus  ends  to  form  a  head  (but  observing  that  their 
length  does  not  interfere  with  the  opposing  teeth  when  in  occlusion), 
and  the  wax  filling  then  molded. 

For  this  purpose  a  hard  wax,  or  one  which  is 
niakina  ^^^  affected  by  the  body  temperature,  should  ahvays 

max  Tnlay.  be  used,   for  the    reason    that    any    wax    which    is 

sufficiently  softened  by  the  temperature  of  the  body 
is  not  reliable,  because  if  the  wax  inlay  yields  or  draws  to  the  slightest 
extent  in  removing  from  the  cavity,  accuracy  of  adaptation  is  thereby 
endangered,  and  no  proof  of  the  correctness  of  the  cavity  preparation 
obtains,  both  of  which  important  features  are  insured  by  the  use  of  a 
hard  wax. 


548 

A  piece  of  such  wax  of  suitable  size  and  shape  should  first  be 
trimmed  to  follow  the  outlines  of  the  cavity,  thus  insuring  its  readily  find- 
ing its  way  to  the  most  extreme  cervical  margin  or  margins,  and  at  the 
same  time  allowing  a  lib-eral  quantity  of  surplus. 

When  so  trimmed  the  wax  should  then  be  heated  to  a  proper,  uni- 
form and  zuorkahlc  plasticity,  which  can  be  done  best  in  hot  water,  or, 
possibly,  by  means  of  electricity,  and  the  piece  then  forced  to  place  with 


# 


f^ 


Figf.  445  B 


considerable  pressure  applied  with  the  thumb.  When  so  seated,  the 
patient  should  be  instructed  to  close  firmly  into  it,  and  to  exercise  all  of 
the  mandibular  movements,  as  in  the  act  of  mastication.  When  this  has 
been  observed  the  wax  should  be  chilled  with  a  spray  of  cOld  water  and 
all  of  the  surplus  gradually  and  carefully  trimmed  away  to  the  cavity 
margins  with  a  warm  sharp  instrument.  A  thin  ribbon  separating  file 
should  then  be  carefully  passed  between  it  and  the  adjacent  tooth,  if  one 
be  present,  and  the  filling  gently  removed  by  inserting  a  pointed  in- 
strument into  the  body  of  it  at  some  favorable  place,  after  which  it  should 
be  finally  trimmed  and  carved. 

Any  pins  used  will  nearly  always  cling  securely  to  the  filling,  but  if 
they  do  not  and  are  found  to  be  loose,  they  should  be  lifted  out  of  the 
wax  and  replaced  in  the  tooth.  The  filling  sliould  then  also  be  replaced 
and  a  hot  pointed  instrument  inserted  into  the  wax  until  the  end  of  each 
pin  is  reached.    This  will  melt  the  wax  around  the  head  of  the  pins  and 


549 

thereby  securely  attach  them,  after  which  the  filHng  should  be  polished 
smooth  with  a  pledget  of  cotton  dipped  in  liquid  vaselin  or  glycerin 
The  approximal  surfaces  may  likewise  be  polished  by  using  a  strip  of 
very  thin  tape  previously  saturated  with  either  of  the  above  and  gently 
dra\v^n  backward  and  forward,  much  as  a  finishing  strip  is  used.  When 
the  wax  filling  is  thus  finished,  it  should  be  carefully  removed  from  the 
cavi'y  and  immediately  invested.     While  some  may  prefer  to  place  the 


f» 


Fig.  446 


Fisf.  447 


wax  filling  in  a  small  jar  partially  filled  with  water,  and  invest  at  a  more 
convenient  time,  it  is  usually  best  to  do  this  immediately  asi  a  precaution 
against  any  possible  accident  or  change  of  form. 

Prior    to    investing,    the    sprue-wire    should    be 
TnvtSting,  heated   as   hot  as   may   be  comfortably  held   in  the 

fingers  and  then  pressed  into  the  inlay  (Fig.  448) 
at  some  thick  and  favorable  point,  and  held  until  cold.  It  should  now  be 
observed  that  the  attachment  of  the  inlay  to  the  sprue-wire  is  securely 
made,  in  order  that  the  possibility  of  its  becoming  loose  and  floating 
around  in  the  investment  may  be  precluded ;  it  is  then  placed  in  position 
in  the  base  of  flask  (Fig.  449). 

An  investment  material  which  possesses  the  combined  qualities  of 
withstanding  heat  without  change  of  form,  of  presenting  a  smooth  sur- 
face and  yet  of  such  texture  as  will  admit  of  the  egress  of  air  which  is 
contained  within  the  mold   after    the    wax    has    been    burned    out,    is 


550 

essential ;  and  the  accuracy  of  adaptation  of  the   completed  filling  will 
largely  increase  in  proportion  as  these  qualities  are  present. 

Such  an  investment  should  be  mixed  of  a  proper  consistency,  which 
may  be  obtained  with  uniformity  by  previously  ascertaining  the  proper 
proportions  each  of  investment  material  and  water,  by  measurement.     As 


Fig.  448 


Fig.  449 


Fig.  450 


Fig.  451 


a  working  basis  two  parts  of  investment  to  one  part  of  water,  by  weight, 
will  usually  afford  a  mix  of  the  proper  consistency,  though  this  may  vary 
with  the  different  materials  now  in  use.  The  "Ansco"  apothecary  scale 
No.  I  (Fig.  450)  will  answer  nicely  for  weighing  water  and  investment. 
When  the  proportions  are  thus  properly  weighed,  they  should  then  be 
thoroughly  mixed,  first  with  the  spatula  and  then  by  rolhng  it  in  a  thin 
layer  around  the  inner  surface  of  the  bowl  until  all  gases  formed  by  the 
chemical  reaction  are  liberated  (Fig.  45  0- 


551 

This  should  be  painted  over  the  surfaces  and  into  the  pits  and 
grooves  of  the  wax  pattern  with  a  small  brush,  and  then  built  up  freely 
as  indicated  in  Fig.  452.  This  primary  coating  of  the  pattern  is  essential 
with  any  investment  material  on  the  market,  but  not  so  great  a  mass 
can  be  built  up  with  the  Taggart  investment,  as  with  the  others  which 
stiffen  quickly  when  mixed.  The  Taggart  investment  has  the  advantage 
of  setting  very  slowly,  although  when  it  does  begin  to  set  the  stiffening 
process  is  quite  rapid.     The  fact  that  the  Taggart  material  when  mixed 


uiijiiiiyiuJiiiiiiiiiiiiiJ"^^ 

Fig.  453 


Fifj.  453 


in  right  proportions  is  almost  as  liquid  as  milk,  and  then  does  not  begin 
to  stiffen  for  several  minutes,  allows  time  for  thoroughly  eradicating  all 
air  bubbles  and  gases  by  rotating  in  a  bowl,  as  already  described,  or  by 
shaking  up  and  down  in  a  large-mouthed  bottle  or  other  suitable  recep- 
tacle. Dr.  Taggart  has  introduced  a  special  rotating  mixing  device  which 
is  very  satisfactory.  When  thoroughly  hardened,  the  base  should  be 
carefully  detached,  the  sprue-wire  heated  and  gently  removed  with  heavy 
pliers  (Fig.  453),  and  the  flask  then  placed  over  the  burner  and  the  wax 
burned  out. 

IMuch  of  the  success  of  the  casting  will  depend 

locating  Up  upon  properly  heating  up  the  flask  and  burning  out 

and  Burning  Out      the  wax,  and  yet  this  must  be  done  in  such  manner 

^^^'  as  will  insure  both,  while  at  the  same  time  conserving 

the  integrity  of  the  investment. 


552 

Where  several  cases  arc  to  be  invested,  heated  up,  and  cast  at  the 
same  time,  it  is  always  well  to  make  some  mark  or  letter  on  the  under 
side  of  the  investment  in  each  flask,  or  with  chalk  on  the  flask  ring,  before 
heating,  as  a  means  of  distinguishing  them. 

Just  as  soon  as  the  investment  has  hardened  and  the  base  and  sprue- 
wire  have  been  removed,  the  flask  should  be  placed  over  a  very  low  flame 
and  allowed  to  remain  at  such  a  temperature  for  five  or  ten  minutes,  or 
until  all  moisture  in  the  investment  has  been  converted  into  steam  and 
evaporated. 


Fig.  454 


The  flame  may  then  be  slowly  and  gradually  increased  until  its 
full  volume  has  been  reached,  at  which  point  the  case  should  be  allowed 
to  remain  until  all  evidences  of  burning  wax  or  gases  emanating  there- 
from, or  of  smoke,  cease.  Altogether  this  will  usually  require  from 
twenty  to  thirty  minutes,  and  the  casting  should  never  be  attempted 
until  such  precautions  have  been  observed^  because  any  gases  confined 
within  the  mold  will  cause  imperfections  in  the  casting. 

When  thus  properly  burned  out,  the  case  should  be  allowed  to  cool 
somewhat  before  casting,  if  possible,  as  experience  seems  to  prove  that 
the  influence  of  heat  and  consequent  expansion  at  the  time  of  casting  is 
more  or  less  noticeable  in  the  degree  of  accuracy  in  the  adaptation,  and 
this  varies,  of  course,  with  the  difi^erent  investment  materials. 

When  the  case  has  been   properly  burned  out 

Castlna.  and  allowed  to  cool  as  much  as  possible,  or  until  only 

warm,  the  casting  should  then  be  made.     All  forms 

of  inlay  attachments  for  bridgework  should  be  cast  with  an  alloy  of  gold 

and  platinum,  or  with  about  22-karat  gold,  for  the  reason  that  pure  gold 

is  much  too  soft. 


553 

An  alloy  of  five  per  cent,  of  platinum  in  pure  gold,  furnishes  what 
appears  to  be  the  ideal  combination  for  this  purpose,  although  22-karat 
gold,  or  coin  gold,  may  be  used.  In  the  use  of  either,  however,  all  parts 
of  the  work — inlays,  crowns,  backing,  etc.,  should  be  cast  with  the  same 
metal  or  alloy,  in  order  that  a  uniform  color  may  present  throughout 
the  finished  piece. 

It  is  also  advisable  to  have  a  considerable  surplus  of  gold  for  each 
casting,  as  undue  economy  in  this  connection  may  be  the  cause  of  in- 
numerable failures  which  might  otherwise  be  avoided,  and  as  such 
surplus  is  not  wasted,  a  liberal  quantity  should  always  be  placed  in  the 
crucible. 

The  gold  or  alloy  to  be  used  should  always  be  melted  and  refined 
previous  to  each  casting.  This  may  be  easily  and  quickly  accomplished  by 
fusing  the  mass  on  a  charcoal  block  and  adding  a  small  quantity  of 
potassium  nitrate  (saltpetre)  or  borax,  or  a  mixture  of  equal  parts  of 
both,  to  the  fused  metal,  and  failure  to  observe  this  precaution  will  usually 
result  in  a  refractory  or  sluggish  fusing,  and  may,  consequently,  give 
an  imperfect  casting. 

Opening  m  *'mtr 

In  cases  where  the  opening  of  the  "bite"  is  indicated  or  demanded  as 
a  means  of  arresting  the  progress  and  influences  of  attrition,  several 
inlays  may  be  made  in  one  piece,  as  illustrated  in  Fig.  454  In  this 
procedure  the  occlusal  surfaces  need  only  be  prepared  to  the  extent  of 
forming  smooth  definite  marginal  edges,  and  holes  for  the  reception  of 
one  or  two  pins  should  be  drilled  into  each  tooth,  observing  that  they  are 
so  placed  as  to  be  in  parallel  lines  with  each  other  and  not  to  impinge 
too  closely  upon  the  pulps. 

With  pins  made  of  about  20  gauge  iridio-platinum  wire,  properly 
threaded,  in  position,  the  wax  should  be  molded  to  the  teeth,  and  to 
conform  to  the  occlusion  when  held  at  the  proper  distance.  This  distance 
must  previously  be  determined  and  temporarily  sustained  by  an  instru- 
ment or  wedge  on  the  opposite  side  of  the  mouth.  When  the  wax  is 
thus  molded,  it  should  be  removed  and  carved  and  the  piece  then  cast. 
A  case  of  opening  the  bite  to  the  extent  of  making  opportunity  for  the 
complete  restoration  of  the  incisor  teeth  with  porcelain  crowns  is  illus- 
trated in  Fig.  455 

A  similar  procedure  will  often  be  found  useful 
Splinting  "''  splinting  and  properly  restoring  the  occlusion  of 

E»0$C  Ccctb.  loose  teeth,  as  illustrated  in  Fig.  45^   the  two  inlavs 

being  made   in   one  piece,   or   they   could  be   made 
separately  and  subsequently  soldered  together. 


554 

In  large  approximo-occlusal    cavities,    whether 

Combination  ^^^  inlay  is  to  be  used  as  an  attachment  for  bridge 

Of  Cast  Gold  and        or  not,  it  is  often  desirable  to  avoid  a  too  conspicuous 

Porcelain  Tnlay.         display  of  gold^  and    thus    obtain    a    more    esthetic 

effect.      This   may   be   easily   accomplished   by   first 

making  the  wax  filling  and  carving  it  as  the  requirements  demand,  and 

then  cutting  a  "cavity"  in  the    wax,    and    subsequently    filling    it    with 

Jenkins's    or    Brewster's    lozv    fusing    porcelain    body    after    the    filling 


BEFORE 


AFTER 

Fig.  455 


has  been  cast.  Such  cavities  may  be  cut  in  the  wax,  if  it  is  hard,  with 
Roach's  "Suction  Carver"  or  with  a  bur  in  the  engine  and  sharp  chisels, 
and  if  made  of  retentive  form,  the  porcelain  is  securely  anchored  therein 
and  will  withstand  the  heat  of  soldering  in  the  final  assemblage  of  the 
filling  to  other  parts  of  the  bridge,  if  care  is  exercised  in  heating  up  and 
cooling  ofif  the  piece  (Fig.  457). 

As  there  is  considerable  difference  in  the  expansion  and  contraction 
of  the  larger  mass  of  gold,  as  compared  with  the  smaller  quantity  of 
porcelain,  extreme  care  is  also  necessary  to  avoid  the  occurrence  of 
checks  or  fractures  in  the  latter  after  baking.  If  the  cavity  margins  in 
the  gold  filling,  however,  are  made  perfectly  smooth,  if  the  porcelain  ie 


555 

not  allowed  to  overlap  upon  them,,  and  then,  if  the  case  is  allowed  to 
become  cold  in  the  muffle  of  the  furnace  after  each  fusing,  and  particu- 
larly after  the  last  one,  such  mishaps  may  be  avoided.  In  the  event  of 
an  imperfection,  the  porcelain  niay  be  completely  removed  from  the 
cavity  in  the  gold  by  placing  the  filling  in  hydrofluoric  acid,  after  which 
it  may  again  be  baked. 

In  any  of  these  procedures  no  apprehension  need 

€a$tina  to  ^^  ^^^^  ^^  ^^  whether  the  metal  to  be  cast  will  alloy 

Surfaces  of  lllCtaK       with  or  become  securely  attached  to  such  bands  or 

dowels,  etc.,  as  are  used,  for  //  the  latter  are  clean 

and  free  from  oxidation  when  the  case  is  invested,  and  if  the  metal  is 


Fig.  456  pi^  ^5- 

sufficientlv  fused  when  the  easting  is  made,  a  physical  union  usually  re- 
sults. In  the  case  of  casting  to  the  extreme  ends  of  dowels,  or  small 
pins,  or  to  the  surfaces  of  clasps,  attachments,  etc.,  however,  they  should 
always  be  notched  or  roughened  as  a  means  of  mechanically  aiding-  in  this 
attachment. 

While  an  alloy  of  base  metals  compounded  and 
Use  Of  Base  metals      advocated  for  all  forms  of  cast  work  called  "Acolite," 
and  Alloys  "metalite,"    etc.,   or    any   of   the     better    grades    of 

amalgam  or  similar  alloys  may  be  used  in  the  con- 
struction of  crown  and  bridgework,  with  good  results  perhaps,  the  use 
of  such  low  grade  metal  is  not  recommended,  nor  are  they  considered  as 
possessing  any  possible  advantage  save  that  of  pure  but  unwholesome 
economy. 

Pin  Eockcd  Tnlavs. 

In  some  cases,  more  especiallx'  in  the  I'jresence  of  living  pulps,  it  is 
desirable  to  use  a  i)in  in  connection  with  an  inlay,  in  order  to  attain 
oreater  security.  When  two  such  abutment  inlays  are  used  and  both 
carry  pins,  it  is  often  found  to  be  difticult  to  set  the  bridge  after  assem- 
bling  the   parts,   because   of   the    difficulty   of  having   the   pins   parallel" 


556 

Moreover,  it  would  be  more  desirable  to  have  the  pins  at  a  tangent, 
if  this  were  possible.  For  this  reason  Dr.  H.  N.  Orr,  of  Chicago,  and 
Dr.  C.  B.  Reynolds,  of  Seattle,  Wash.,  have  conceived  the  idea  of  having 
the  pins  separable  from  the  inlays,  and  so  constructed  that  they  may  be 
inserted  at  the  time  of  cementation. 

The  technique  is  as  follows :  After  properly  preparing  the  cavity,  the 
wax  inlay  is  made,  and  an  iridio-platinum  pin  set  in  the  usual  way.  The 
pin  is  then  slightly  warmed  and  removed,  and  in  its  place  introduced  a 


Fig.  458 


Fig.  459 


Fig.  460 


carbon  of  the  same  gauge.  These  carbons  are  of  various  sizes,  from 
I  ^  to  20  gauge,  and  may  be  threaded  or  roughened  to  make  them  remain 
more  securely  in  the  wax. 

Fig.  458  represents  two  teeth  prepared,  and  above  them  are  two  wax 
inlays  with  the  carbons  in  place. 

Fig.  459  at  A  and  B,  shows  sections  of  the  cavities,  inlays  and 
carbons,  while  at  C  and  D,  in  Fig.  460  are  seen  occlusal  surfaces  and 
the  openings  for  the  carbons.  When  the  inlay  is  cast,  the  carbon  is  removed, 
inserting  in  its  place  an  iridio-platinum  pin,  and  an  extension  into  the 
tooth  of  the  same  gauge  as  the  pin  is  then  made.  Tliis  is  an  advantage, 
as  by  this  means  the  little  hole  which  is  to  receive  the  pin  may  be  drilled 


557 

into  the  tooth  after  the  casting  is  made,  and  may  be  done  very  accurately. 

Fig.  461    represents  the  finished  bridge;  the  abutments  with  iridio- 

platinum  pins  showing  at  E  and  G  and  the  dummy  at  F.    In  setting  the 


Fig  461  Fig  462 

bridge,  cement  is  also  used  for  seating  the  pins,  and  these  are  driven 
securely  into  position,  and  the  excess  of  pin  is  then  ground  flush  with 
the  occlusion. 

It  may  be  an  advantage  in  some  cases  to  thread  the  pin  and  then 
tap  the  hole  through  the  inlay,  and  even  into  the  tooth  itself,  thus  making 
it  possible  to  screw  the  pin  into  place. 

Fig.  462  shows  the  bridge  after  it  is  set,  the  dotted  lines  indicating 
the  seating  of  the  inlays  in  the  cavities  and  the  position  occupied  by  the 
pins. 

In  the  use  of  any  of  the  various  forms  of  separ- 

Porcclam  ^^^^  dowel  crowais  with  cast  bases  as  abutment  pieces 

(frowns  as  JIbUtmcnt     for  bridgework,  each  crown  to  be  so  used  should  be 

Pieces.  first  adapted   directly  to  the   root   in   the  mouth   in 

accordance  with  the  requirements  and  in  the  m»iiner 

indicated  in  connection  wath  single  crown  work,   and  if  there  be  mo^e 

than  one  crown  in  the  same  case,  each  should  be  completed  separately. 

The  only  difference  in  the  detail  of  procedure  as  outlined  for  single 
crowns,  lies  in  the  fact  that  the  approximal  surface  of  the  porcelain  crown 
presenting  toward  the  space  to  be  filled  with  artificial  teeth,  must  be  so 
grooved  out  or  ground  away  as  to  permit  the  wax,  and,  subsequently,  the 
cast  base,  to  extend  well  down  toward  the  occlusal  or  incisal  end  and 
beyond  the  contact  point,  as  a  means  of  aflfording  sufficient  surface  of 
metal  to  insure  ample  strength  in  the  subsequent  attachment  of  the  cast 
base  to  the  adjacent  portion  of  the  bridge,  with  solder.      (Fig.    4^\]) 

Where  the  root  to  be  crowned  stands  alone,  and  artificial  teeth  are  to 
be  placed  adjacent  to  it  on  both  sides,  then,  of  course,  both  approximal 
sides  of  the  porcelain  crown  must  be  so  ground  for  the  same  reason,  as 
illustrated  in  Fig.  464 


558 

When  thus  ground  and  the  wax  base  properly  molded  and  trimmed, 
the  sprue  wire  should  be  attached  (Fig.  465)  and  the  base  cast,  after 
which  the  porcelain  should  be  temporarily  placed  in  position,  and  the  base 
finished  to  the  point  of  polishing. 


Fig.  463 


Fig.  464 


Fig.  465 


When  gold   crowns  are   indicated  as  abutment 

Gold  drowns  pieces  for  fixed  bridgework,  the  same  general   line 

as  Jibutment  of  procedure  suggested  for  separate  crowns  should 

Pieces.  be  observed.     Prior  to  this,  however,  it  must  also 

and  always  be  noted  that  the  approximal   surfaces 

of  the  supporting  root,  or  roots,  are  ground  away  until  parallel  with  the 

long  axis  of  the  tooth,  and  with  the  other  supporting  teeth,  in  order  to 

insure  the  ready  adjustment  of  the  completed  fixture. 

After  the  crown  has  been  cast,  it  should  be  finished  to  the  point  of 
polishing  and  then  fitted  to  position  on  the  root. 

After  all  of  the  attachments  or  abutment  pieces 
"Bite"  and  have  thus  been  completed  separately,  they  should  be 

Impression.  placed  in  position  on  the  supporting  teeth  and  the 

"bite"  and  impression  taken. 


559 

Where  inlays  are  used  it  is  often  well  to  primarily  finish  only  the 
marginal  edges,  and  then  to  allow  a  small  projection  of  the  "sprue"  to 
remain  (Fig.  466)  until  the  "bite"  and  impression  have  been  taken.  Where 
this  is  possible,  and  particularly  in  flat-surface  inlays  for  anterior  teeth, 
the  correct  position  of  the  inlay  in  the  impression  is  thus  more  easily 
obtained  and  more  securely  sustained,  and  these  are  highly  important 
features. 

When  porcelain  crowns  with  cast  bases  are  used,  both  the  crown  and 
its  base  should  be  in  position  on  each  root  when  the  bite  and  impression 
are  taken. 


Fig  466 


When  each  piece  is  thus  finally  adjusted  to  proper  position  on  the 
supporting  roots,  the  "bite"  and  impression  should  be  taken,  the  former  in 
wax  and  the  latter  always  in  plaster. 

After    carefully   observing   that    each    piece   is 
models.  forced   well   down   in  place   in   the   impression   and 

held  with  a  small  quantity  of  melted  wax,  if  neces- 
sary, the  impression  should  be  properly  varnished  and  filled.  The 
model  should  invariably  be  made  of  a  good  strong  investment  material, 
because  it  then  never  becomes  necessary  to  detach  the  abutment  pieces 
therefrom  in  the  subsequent  final  assemblage  of  the  several  parts  by 
soldering. 

When  thus  filled  and  separated,  the  "bite"  should  be  adjusted  and 
tihe  case  then  mounted  on  the  articulator. 

After  the  models  have  been  thus  obtained,  some 
€on$tructitia  suitable   form  of  replaceable  bridge    tooth    for    bi- 

PostcrlOl*  Dummies,      cuspids  and  molars,  such  as  is  made  by  the  Con- 
solidated Dental  Mfg.  Co.    (see  Fig.    434)    or    the 
Pennsylvania  Dental  Mfg.  Co.  (sec  Fig.  435).  should  be  selected  to  meet 
the  requirements  of  size  and  color  and  properly  ground  to  the  desired  ad- 
justment.    It  should  then  be  observed  that  the  approximal  sides  of  each 


56b 

porcelain  tooth  is  sufficiently  grooved  out  so  as  to  admit  of  carrying  the 
tvax,  and  subsequently  the  gold  backing,  well  over  upon  these  surfaces, 
thus  forming  a  finishing  line  for  the  backing,  and  more  completely 
"boxing"  up  each  tooth,  thereby  insuring  a  maximum  of  strength  both 
in  the  backing  and  in  its  subsequent  attachment  to  the  abutment  pieces 
with  solder,  and  affording  a  cleaner  interproximal  space  between  each 
tooth  (Fig.  467 ). 

While  any  of  the  various  makes  of  detachable  dowel  crowns  may 
often  be  used  in  the  same  manner  by  grinding,  these  special  bridge  teeth 


Fig.  467 


are  more  universally  applicable  because  of  being  thinner  on  the  lingual 
sides,  and  consequently  requiring  less  grinding  upon  these  surfaces. 

When  ground  to  the  proper  and  required  adjustment  to  gum  and 
occlusion,  it  should  then  be  determined  as  to  what  form  should  be  given 
to  the  lingual  surface  of  the  backing  which  is  to  support  the  porcelain 
teeth ;  whether  it  should  taper  from  the  cusps  of  the  porcelain  dummy  to 
a  small  contact  with  the  ridge  at  the  neck  (Fig.  468),  or  whether  it 
should  be  broader  and  rest  upon  the  gum  in  the  form  of  a  saddle  (Fig. 
469),  and  this  is  to  be  governed  largely  by  the  degree  of  absorption,  the 
shape  of  the  ridge,  and  the  occlusion  of  the  opposing  teeth. 

If  these  latter  conditions  are  favorable,  the  pos- 
SaddlC  sibilities   for    securing  an   accurate   adaptation   of  a 

TormatiOli.  narrow  saddle  to  the  gum  often  makes  this  type  of 

construction  preferable  for  the  reason  that  the  lingual 
contour  of  the  intervening  artificial  teeth  is  thus  restored,  and  if  the  saddle 
is  narrow  and  well  adapted^  such  surfaces  are  usually  kept  cleaner  than 
are  those  where  the  lingual  contour  is  not  restored  and  which  are  there- 
fore more  inaccessible. 


56i 


max 

Backing. 


As  soon  as  this  feature  of  construction  has  been 

determined   and    the   teeth   have   been   selected    and 

ground,  each  tooth  should  first  be  separably  backed 

up   with   wax.     While  the   best   results   are   to   be 

obtained  by  using  the  pins  which  are  especially  made  for  some  forms  of 

these  teeth  because  of  their  uniform  size,  it  is  possible,  however,  to  make 


Fig.  468 


h'ig.  469 


a  suitable  pin  of  iridio-platinum  wire  about  14  gauge,  or  to  make  a 
wax  pin  to  fit  the  hole  in  the  tooth  as  a  part  of  the  backing,  and  this  will, 
of  course,  be  reproduced  and  subsequently  become  a  part  of  the  casting 
itself. 


« 


Fig.  470 


Fig.  471 


If  the  special  pins  are  used,  preference  should 
Special  Pins.  be  given  to  those  made  of  iridio-platinum,  gold  and 

platinum,  or  clasp  metal,  for  the  reasons  previously 
mentioned.  In  their  use  the  lingual  surface  of  each  tooth  should  first  be 
painted  with  glycerine  or  liquid  vaseline,  the  pin  properly  fitted  as  to 
length  and  placed  in  position  in  the  tooth  (Fig.  470).  and  a  suitable  hard 
wax  then  melted  around  the  exposed  end  of  the  pin  and  over  the  surface 
of  the  porcelain  (Fig.  47 1')- 

In  the  absence  of  such,  however,  suitable  pins 

Ca$tPin$.  uiay  be  easily  made  as  a  part    of    the    casting    by 

lubricating  the  interior  of  the  hole  in  the  crown  and 

gently  forcing  the  end  of  a  small  piece  of  warm  hard  wax,  suitably  shaped, 


562 

into  it,  and  afterward  pressing  and  molding  the  surplus  end  over  the 
surface  ©f  the  porcelain  (Fig.  472). 

When  this  has  been  done  with  each  tooth,  the  surfaces  of  the  model 
and  attachments  thereon  should  be  similarly  lubricated  to  prevent  the  wax 


Fig.  •173 


from  adhering  thereto,  and  a  piece  of  moderately  soft  prosthetic  wax  then 
molded  to  place.  Each  tooth  with  its  wax  backing  should  now  be  forced 
into  this  until  assuming  its  proper  relation  to  model  and  attachments, 
after  which  the  wax  should  be  carved  to  the  desired  outline. 

While  a  separate  backing  may  be  made  for  each 
Sectional  BiCkingS.  tooth  in  this  manner,  and  less  display  of  gold  ahvays 
obtains  as  a  result  of  backing  each  tooth  separately, 
still,  in  cases  where  some  little  gold  in  between  the  porcelain  teeth  may 
not  be  objectionable,  it  is  unnecessary,  as  one  investment  and  one  casting 
will  answer  equally  well  for  two,  three  or  even  four  teeth  in  one  piece,  or 
for  as  many  as  may  constitute  one  section  of  the  bridge  betzueen  abut- 
ments (Fig.  473).  Such  sections  may  be  made  in  much  less  time,  and 
will  afiford  even  better  results  in  the  finished  piece,  because  of  minimizing 
the  number  of  pieces,  and  of  thus  involving  less  detail  and  requiring  but 
a  minimum  of  solder  in  the  final  assemblage. 

After  thus  trimming  and  shaping  the  wax  to  meet  all  of  the  require- 
ments of  the  finished  backing,  each  porcelain  tooth  should  be  carefully 
detached,  then  replaced  and  removed  several  times,  in  order  to  obtain 
perfect  freedom  in  their  adjustment  to  the  wax,  and  then  laid  aside  until 
the  casting  has  been  made. 

The  sprue-wire  should  then  be  securely  attached  (Fig.  474),  the  case 
invested,  and  the  casting  made,  after  which  it  should  be  cleaned  by  placing 
tn  hydrofluoric  or  heated  hydrochloric  acid,  until  all  particles  of  invest- 
ment material  have  been  removed.  The  acid  is  then  neutralized  by  dip- 
ping the  piece  in  a  solution  of  soda,  when  each  porcelain  tooth  should  be 


5^3 

carefully  fitted  to  place  and  the  whole  then  finished  with  stones  and  disks, 
and  fitted  closely  to  the  model. 

The  correct  relation  of  each  piece  to  the  model  should  now  be  effected 
and  sustained  with  hard  wax,  after  which  all  of  the  porcelain  teeth  should 
be  removed  and  the  case  invested  for  the  final  assemblag"e  of  the  backing, 
or  backings,  to  the  abutment  pieces. 


Fig  i73 


The  model  having  been  made  of  investment  material,  it  is  now  only 
necessary  to  first  allow  it  to  become  thoroughly  saturated  with  water^  and 
then  add  to  it  a  sufficient  quantity  of  freshly  mixed  investment  material  of 
the  same  character,  to  sustain  the  relation  of  the  parts  during  the  heating 
up  and  soldering  process,  which,  because  of  the  absence  of  any  porcelain, 
may  be  more  or  less  quickly  accomplished. 

When  assembled,  the  piece  should  again  be  treated  to  the  acid  bath, 
and  when  thoroughly  clean  and  dry,  the  porcelain  teeth  should  be  cemented 
to  place  and  the  case  afterward  finally  and  nicely  finished. 

The  ordinary  diatoric,  or  pinless,  or  even  vulcan- 

Use  Of  Diatoric         ^^^  teeth  may  also  be  used  in  similar  manner.  In  the  use 

and  Uulcanite  tcetb.      of  ^l^e  former  the  lateral  holes  extending  to  the  ap- 

proximal  surfaces,  which  are  found  in  some  makes. 

are  an  element  of  weakness,  and  since  they  can  not  be  used  in  this  work, 


564 

they  should  therefore  be  filled  with  low-fusing  porcelain  body  before  being 
ground  to  the  proper  adjustment. 

Vulcanite  teeth  may  also  be  successfully  used  by  temporarily  enlarg- 
ing the  body  of  the  pins  to  the  same  diameter  of  their  heads  with  wax  or 
cement,  and  then  lubricating  the  whole  and  adapting  wax  backings.  When 


Fig  474 


Figr  475 


the  backing  has  been  cast  and  assembled  to  the  other  parts  of  the  bridge, 
the  material  used  to  temporarily  enlarge  the  pins  for  the  purpose  of 
admitting  of  the  detachment  of  the  wax  backing  may  be  removed  and  the 
tooth  or  teeth  then  cemented  to  place.  Or  small  platinum  tubes  with  a 
soldered  joint  and  one  end  closed  up,  and  of  a  proper  size  to  fit  over  each 
pin,  may  be  made,  placed  in  position,  the  wax  backing  securely  attached 
to  them,  and  the  casting  made  over  and  around  them. 

Ordinary  long  pin  flat-back  facings  may  also  be 

Use  Of  Ordinary         used,   either  as  previously   suggested  in   connection 

Cong  Pin  TaciitflS.       with  single  crown  work   (see  Fig.  415),  or  in  the 

manner  described  as  applying  to  the  use  of  vulcanite 

teeth,  and  the  entire  occlusal  as  well  as  lingual  surfaces  properly  formed  in 

wax  and  subsequently  reproduced  in  gold  (Fig.  475). 

In  cases  of  very  close  "bites"  combined  with  a  strong  occlusion,  or 
a  powerful  occlusal  stress,  or  where  the  cosmetic  requirements  are  not 
a  prominent  factor,  this  type  of  construction  may  occasionally  be  indi- 
cated. 


56 


^0 


While  any  of  these  latter  forms  of  teeth  may  also  be  used  by  casting 
directly  to  them,  this  procedure  is  not  recommended  for  the  reasons  pre- 
viously mentioned,  and  particularly  when  gold  or  any  of  its  alloys  is  used 
in  the  construction  of  the  work. 

In  many  instances  where  the  cosmetic  require- 

6oW  DutnntiCI.        ments   do  not  demand,  and  where   the  exceedingly 

powerful  stress  of  occlusion  does  not  indicate  the 

use  of  porcelain,  all-gold  dummies  may  be  easily  made  in  single  form  or 

in  sections,  by  molding  wax  to  fit  the  space,  the  model,  and  the  occlusion 

(Fig.  476)  on  the  articulator  and  reproducing  it  by  casting,  and  this  pro- 


Figr.  476 


Fig:.  -tT? 


cedure  will  be  found  particularly  useful  in  the  construction  of  so-called 
"self-cleansing"  bridges,  or  where  only  the  occlusal  surfaces  are  necessary 
(Fig.  477). 


€on$trttctina  Jimcrlor  ^'Dummies." 

In  the  construction  of  bridges  which  involve  the  replacement  of  an- 
terior teeth,  the  abutment-pieces  should  be  made  separately,  as  previously 
indicated,  and  when  all  are  finished  should  be  placed  in  position  on  the 
supporting  teeth  or  roots,  and  the  "bite"  and  impression  taken.  The 
model  should  then  be  made  of  investment  material,  the  bite  adjusted  and 
the  case  mounted  on  the  articular.  A  typical  case,  where  the  four  in- 
cisors are  supplied  by  attachment  to  the  cuspid  ropts  in  the  form  of 
separable  dowel  crowns  with  cast  bases,  is  illustrated  in  Fig.  47S. 

The  type  of  porcelain  tooth  which  seems  best  adapted  to  the  require- 
ments of  the  case  at  hand  should  now  be  selected  and  ground  to  fit  the 
model  and  to  otherwise  conform  to  the  requirements.  Wherever  possible, 
some  form  of  replaceable  tooth  or  facing  should  be  given  the  preference 


566 

for  the  reasons  mentioned,  though  ordinary  facings  may,  of  course,  be 
used,  and  backed  up  either  in  the  usual  manner  or  by  casting. 

The  special  form  of  facing  with  separate  pins 

K^plac^abk  Tacings,      will  be  found  to  be  more  or  less  universally  applicable, 

and  when  this  type  is  available,  suitable  ones  should 

be  sdected  and  ground  to  the  proper  adaptation,  with  a  slight  bevel  at 

the  incisal  edge. 


Fig.  478 


^'vtJti' 


FijT.  479 


The  lingual  surfaces  should  then  be  coated  with  glycerin  or  oil,  the 
pins  placed  in  position,  and  hard  wax,  such  as  is  used  for  inlays  melted 
and  run  over  the  entire  surface  until  a  thin  backing  is  thus  formed. 

The  model  should  then  be  varnished  with  shellac  and  then  with 
glycerin  or  oil,  a  rim  of  fairly  soft  prosthetic  wax  molded  and  attached 
to  it  with  a  hot  instrument,  and  each  tooth  with  its  pins  and  hard  wax 
backing  then  forced  to  place  in  this.  When  the  proper  and  desired  ad- 
justment has  been  secured  and  sustained  by  melting  the  softer  wax,  the 
entire  section  of  backings  should  be  formed  and  carved  to  the  require- 
ments. 

Each  facing  should  now  be  gently  lifted  off  (Fig.  479)  and  the  sprue- 
wire  attached  at  a  favorable  point  somewhere  near  the  center,  and  the 
piece  invested  and  cast. 


567 

One  sprue-wire  is  all  that  will  usually  be  found  necessary  for  casting 
the  backings  of  three  or  even  four  teeth,  and  it  is  seldom  that  any  one 
section  will  include  more  than  this  number  between  abutment-pieces.  In 
the  event  of  larger  sections,  however,  provision  should  be  made  for  addi- 
tional "gates,"  such  as  is  indicated  for  large  castings,  and  which  will  be 
described  in  connection  with  '^Vemovable"  fixtures. 

When  the  section  has  been  cast  and  then  thoroughly  cleaned  in  acid, 
it  should  be  finished  to  the  point  of  polishing,  in  which  it  is  necessary  to 
observe  that  any  small  projections  or  nodules  of  gold  which  might  inter- 
fere with  the  proper  adjustment  of  the  facings  are  removed  with  a  sharp 


Fisr.  480 


blade,  or  with  a  bur  in  the  engine.  These  are  sometimes  present  as  a 
result  of  too  coarse  or  improperly  manipulated  investment  materials,  and 
can  only  be  avoided  by  observing  the  technique  in  this  particular,  as  pre- 
viously outlined. 

The  section  with  the  facings  temporarily  in  position  should  now  be 
fitted  to  place  on  the  model  and  very  slightly  imbedded  therein  by  first 
marking  the  outline  of  the  casting  in  its  proper  relations,  then  removing 
it  and  trimming  off  the  surface  of  the  model  within  this  outline  to  a 
limited  but  uniform  extent,  averaging,  perhaps,  the  thickness  of  a  piece 
of  thin  blotting-paper  (Fig.  4S0). 

The  piece  should  then  be  again  placed  in  position  and  its  relation  to 
the  model  and  abutment-pieces  securely  sustained  with  hard  wax,  after 
which  the  facings  should  be  carefully  removed  and  the  case  then  invested 
as  suggested  in  connection  with  posterior  dummies. 

When  the  assemblage  has  been  made  with  just  enough  22-karat  or 
20-karat  solder  to  fill  the  immediate  joints  between  the  section,  or  between 
the  sections  and  the  abutment-pieces,  the  case  should  be  again  cleaned  in 
acid,  both  it  and  the  facings  dried  with  warm  air,  and  the  latter  cemented 
to  position  with  a  cement  closely  approximating  the  color  of  the  teeth.    As 


56^ 

soon  as  the  cement  has  thoroughly  crystalhzed,  the  piece  should  then  be 
finished,  polished  and  mounted. 

The  selection  and  grinding  of  duplicate  facings  at  the  time  of  con- 
structing the  piece  and  their  preservation  is  a  valuable  safeguard  at  all 
times,  but  if  this  is  not  observed  the  make,  color  and  mold  of  the  tooth 
used  should  always  be  recorded. 

Wherever  the  extent   of  absorption,   combined 
Replaceable  Crowns      ^^^^  favorable  occlusion  will  admit  of  the  use  of  any 
UstA  as  Dummies.       of   the   various    forms   of   separable    dowel   crowns 
instead  of  facings,  their  use  offers  the  additional  ad- 
vantages of  lingual  contour  and  absence  of  metal  backing  extending  to 


Fig.  481 


the  incisal  end,  thus  affording  increased  artistic  and  esthetic  possibilities. 
They  are  applicable,  however,  only  to  such  cases  as  present  adequate 
space,  or  to  those  cases  where  a  saddle  resting  upon  the  gum  is  indicated 
and  may  be  used  to  support  them. 

When  used  in  connection  with  a  saddle,  some  display  of  gold  between 
the  necks  of  the  crowns  is  unavoidable,  and  where  this  is  objectionable 
such  a  type  of  construction  is  not  indicated.  Any  considerable  display 
of  metal,  however,  may  be  overcome  by  grinding  a  groove  in  the  ap- 
proximal  surfaces  of  each  crown,  as  recommended  in  connection  with  the 
construction  of  porcelain  crowns  with  cast  bases  as  abutment-pieces  for 
fixed  bridgework,  and  grinding  the  lingual  surfaces  much  shorter  than  the 
labial,  thus  admitting  of  the  formation  of  a  backing  instead  of  a  saddle, 
and  insuring  strength  in  their  assemblage  (Fig.  481)- 

The  ordinary  long  pin  facings  now  in  common 
Ordinary  TaclngS.       use  may  also  be  used  in  replaceable  form  and  in  con- 
nection with  a  cast  backing,  either  separately  or  in 
sections,  in  exactly  the  same  manner  as  suggested  in  single  crown  work. 


5^9 

In  the  use  of  these  facings,  however,  and  when  the  backing  is  to  be  cast, 
the  best  results  are  usually  to  be  obtained  by  first  adapting  a  thin  backing 
of  pure  gold  to  each  faci)ig  and  casting  direct  to  this,  by  using  graphite 
pins  (Fig.  482),  and  the  wax  backings  and  castings  may  be  made  in  sec- 
tions, including  as  many  teeth  as  are  used  between  the  abutment-pieces, 
or  each  one  may  be  made  separately,  and  subsequently  united  with  solder. 
The  only  objection  to  this  type  of  facing  used  in  this  manner  lies  in 
the  necessary  thickness  of  the  backing  immediately  surrounding  the  pins, 
though  this  may  be  somewhat  reduced  by  shortening  them.  Facings  so 
used  afford  the  advantages  of  better  protection  against  fracture,  either  in 


r 


Fisr.  4X3 


the  assemblage  by  soldering,  or  in  the  mouth ;  of  replacement  in  the  event 
of  breaking ;  and  of  preservation  of  color  because  of  being  attached  with 
cement ;  while  a  cast  backing,  as  compared  with  one  made  by  burnishing 
or  swaging,  affords  the  advantages  of  greater  and  more  uniform  strength 
combined  with  better  form,  or  increased  artistic  possibilities. 

Steele's  replaceable  facings  may  also  be  used  in 

Steele's  or  €P$liti'$      similar  manner  by  first  grinding  them  to  meet  the 

Replaceable  facings,     requirements  and  then  burnishing  and  trimming  the 

backings    which    accompany    them    to    the    proper 

adaptation.    Facings  and  backings  should  then  be  assembled  on  the  model. 

the  backings  waxed  together,  and  additional  wax  then  added  to  permit  of 

reinforcing  and  carving  to  the  desired  form,  after  which  the  facings  may 

be  removed  and  the  section  cast  all  in  one  piece  and  directly  against  the 

thin  backings.     Where  very   thin   facings   are   demanded,   this   type  of 

duraniy  or  tlie  one  designed  by  Dr.  Evslin  will  be  fouinl  more  or  less 

universally  apiilicable  to  the  six  or  eight  anterior  teeth,  and  may  be  thus 

used  to  good  advantage,  though,  because  of  the  slot  through  the  center, 

neither  is  regarded  as  being  as  strong  a  facing  as  the  one  suggested  by 

the  author. 


570 


Cvpical  €c$e$. 

A  typical  illustration  of  the  possibilities  of  the  casting  process  as 
applied  to  crown  and  bridgework,  and  embracing  esthetic  features,  com- 
bined with  a  degree  of  accuracy  of  adaptation  with  a  maximum  of  strength 
and  a  minimum  display  of  metal,  together  with  the  indisputable  and 
incalculable  advantages  to  be  obtained  by  the  use  of  detachable  or  re- 
placeable porcelain  crowns  and  facings  in  a  manner  heretofore  and  other- 


a 


Fitf.  483 


wise  impossible,  at  least  to  a  degree  which  puts  previous  efiforts  to  shame^ 
is  evidenced  in  the  following  more  or  less  extensive  and  interesting  case. 

The  three  views  of  the  casts  designated  as  Fig.  4S3  A,  B  and  C. 
show  the  case  as  it  presented,  and  illustrate  a  very  unusual  degree  of 
undcr-dcvelopment  of  the  dental  arches  and  teeth,  in  the  mouth  of  a 
young  lady,  eighteen  years  of  age,  who  was  otherwise  perfectly  developed. 

The  temporary  molars  on  each  side  and  in  both  arches  had  been 


571 

retained,  occupying  the  space  of  the  bicuspids  which  had  never  erupted; 
no  lower  lateral  incisors,  nor  any  of  the  second  or  third  molars  in 
either  arch  had  made  their  appearance,  and  the  crowns  of  the  sixth- 
year  molars,  cuspids  and  incisors,  which  had  erupted,  were  malformed  and 
dwarfed  to  such  an  extent  that  their  occlusion  brought  the  lower  jaw  into 
such  close  proximity  with  the  nose  as  to  completely  destroy  all  of  the 
lines  which  give  harmony  and  expression  to  the  lower  third  of  the  face. 

As  may  be  expected,  this  condition  resulted  in  a  degree  of  disfigure- 
ment such  as  is  usually  observed  in  the  edentulous  mouth  of  old  age,  but 
such  as  would  be  embarrassing  even  to  middle  age,  must  less  to  youth 
and  beauty. 

In  studying  the  case  with  a  view  to  ascertaining  the  best  means  of 
bringing  about  such  changes  as  the  restoration  of  the  features  of  the  face 
demanded,  it  seemed,  at  first,  necessary  to  resort  to  orthodontia,  and  to 
so  change  the  position  of  the  roots  of  the  teeth  as  to  permanently  modify 
or  relieve  the  disfigurement. 

A  series  of  skiagraphs  showed  the  roots  of  these  teeth  to  be  abnor- 
mally large  and  well-developed  and  gave  no  evidence  of  the  hidden 
presence  of  any  of  the  missing  teeth,  not  even  the  third  molars. 

Several  consultations  with  prominent  orthodontists,  and  a  careful 
study  of  reconstructed  models,  measurements,  etc.,  together  with  the  age 
of  the  patient  and  the  anxiety  to  have  something  done  in  the  shortest 
possible  space  of  time  finally  led  to  an  abandonment  of  the  idea  of  regu- 
lating, and  to  the  conclusion  that  the  best  results  were  to  be  obtained  by 
removing  the  temporary  molars,  which  were  somewhat  loose  and  more  or 
less  decayed,  opening  the  bite  to  the  required  distance  by  lengthening  the 
sixth-year  molars,  and  replacing  the  temporary  molars  and  all  of  the 
dwarfed  crowns  of  the  incisors  and  cuspids  with  artificial  ones  of  proper 
prominence  and  proportionate  size. 

In  accomplishing  this  the  temporary  molars  were,  of  course,  first 
removed.  The  "bite"  was  then  opened  to  the  required  extent,  which  was 
a  full  half  inch,  by  elongating  the  upper  right  sixth-year  molar  with  a 
cast  gold  crown  to  a  length  corresponding  with  the  desired  length  of  the 
upper  incisors,  and  then  building  up  the  lower  molar  with  an  inlay  made 
to  occlude  with  this  and  to  sustain  the  new  closure  at  the  desired  point. 
These  two  pieces,  opened  the  bite  to  a  degree  demanded  by  the  desired 
restoration  of  the  features  of  the  face,  and  sustained  this  closure  during 
the  construction  of  all  of  the  work. 

A  full  crown  was  used  on  the  upper  molar,  and  an  inlay  on  the 


572 

lower  only  because  each  seemed  best  adapted  to  the  respective  tooth. 
Both  teeth  were  devitaHzed,  however,  and  the  inlay  carried  a  good-sized 
dowel  extending  well  down  into  the  pulp-chamber. 

As  soon  as  these  were  completed,  the  same  procedure  was  followed 
on  the  opposite  side  of  the  mouthy  and  when  the  four  pieces  were  finished 
they  were  temporarily  placed  in  position  on  the  supporting  teeth,  and 
impressions  taken  in  plaster,  after  a  bite  in  wax  had  been  obtained.  Casts 
were  then  made  and  mounted  upon  the  articulator. 

These  casts  were  used  only  for  the  purpose  of  selecting  detach- 
able porcelain  crowns  of  suitable  size  and  shape  to  fill  the  space  and  to 
meet  the  esthetic  requirements — a  very  important  procedure  where  a 
definite  space  is  to  be  filled,  and,  after  cutting  off  the  plaster  teeth,  these 
were  selected  in  pairs,  or  with  a  duplicate  for  each. 

By  this  means  the  position  of  the  right  upper  cuspid  crown  in  its 
relation  to  the  supporting  root  was  correctly  ascertained,  and  the  natural 
crown  was  then  excised,  the  basal  end  of  the  root  suitably  prepared, 
and  the  porcelain  crown  ground  and  otherwise  adapted  to  the  proper 
adjustment  in  the  mouth,  in  which  procedure  the  duplicate  crown  on  the 
model  may  be  used  as  a  guide,  and  will  materially  facilitate  accuracy. 

A  disc  of  36-gauge  pure  gold  was  then  burnished  to  the  root,  the 
dowel  adjusted,  and  soldered  thereto,  and  the  base  then  molded  in  wax, 
and  cast,  as  previously  described.  The  use  of  the  disc  of  pure  gold  facili- 
tates the  molding  of  the  wax  base  to  crown,  root  and  dowel,  and  insures 
a  close  adaptation  to  the  end  of  the  root,  and,  if  the  crown  has  been 
ground  to  a  close  joint  with  the  labial,  or  buccal,  surface  of  the  root, 
the  display  of  any  metal  at  this  point  in  the  finished  crown  is  eliminated. 

When  the  base  had  been  cast,  this  crown  was  then  finished  up  to  the 
point  of  cementing  the  porcelain  to  the  base.  Both  the  base  and  porce- 
lain crown  were  then  placed  in  position  on  the  root,  together  with  the 
gold  crown  for  the  molar,  an  impression  taken  in  plaster,  and  the  cast 
made  of  investment  material. 

The  bicuspid  dummy  which  was  to  take  the  place  of  the  temporary 
molars  removed,  the  space  having  been  diminished  in  consequence  of  the 
size  of  the  cuspid  crown,  was  then  ground  to  the  proper  adjustment  on 
this  model,  a  wax  backing  made  for  it,  and  the  casting  then  made.  After 
casting  the  backing,  it  was  finished  and  assembled  directly  on  this  model 
by  sustaining  its  position  with  hard  wax,  removing  the  two  porcelain 
crowns,  adding  a  small  quantity  of  investment  material  sufiicient  only  to 
hold  the  parts  together,  and  soldering. 

When  this  piece,  comprising  the  molar  crown,  the  cuspid  crown  and 
the  intervening  bicuspid  dummy,  was  roughly  finished,  the  duplicate 
porcelain  crowns  were  then  ground  to  Ht  their  respective  backings,  after 


573 

which  they  were  numbered  "one"  and  "two"  with  ink,  and  then  laid 
aside.  The  original  crowns  were  now  cemented  to  place  and  the  piece 
finished  and  polished. 

The  lower  bridge  on  this  same  side,  which  carried  two  bicuspids 
dummies,  each  backed  separately,  was  then  made  in  identically  the  same 


Fig.  iU 


manner,  and  constructed  to  occlude  properly  with  the  upper  one.  When 
these  were  completed,  the  final  mounting  was  deferred  until  the  two 
bridges  on  the  opposite  side  had  been  completed,  and  these  w'ere  built 
in  exactly  the  same  manner,  and  made  with  the  finished  bridges  for  the 
opposite  side  temporarily  in  position,  in  order  to  conform  to  the  same 
occlusion. 

When  the  four  bridges  were  completed  they  were  all  permanently 
mounted  at  the  same  sitting,  thus  establishing  the  new  closure  of  the 
mandible  with  the  resultant  stress  assumed  by  teeth  on  both  sides  of  the 


574 


arch,  thereby  avoiding  the  soreness  and  discomfiture  which  might  be 
caused  by  throwing  the  stress  upon  only  a  few  teeth  at  first. 

With  the  four  bridges  permanently  mounted,  the  four  upper  incisor 
crowns  were  then  made,  following  the  same  technique,  but  making  the 
two  laterals  first,  and  then  the  centrals,  in  order  that  the  proper  division 
of  the  space  may  be  observed,  and  in  each  case  grinding  and  numbering 
the  duplicates  before  cementing  the  original  crowns  to  place  on  their 
respective  bases. 

When  these  were  finished  and  mounted,  porcelain  jacket  crowns 
were  then  made  for  the  lower  central  incisors.  These  were  made  in 
preference  to  dowel  crowns,  for  the  reason  that  the  shape  and  size  of 
these  teeth  seemed  more  favorable  to  the  adjustment  of  a  telescoping 
instead  of  a  dowel  crown. 


Fig.  485 


In  this  connection  it  will  be  observed  that  no  effort  was  made  to 
supply  lower  lateral  incisors,  it  being  previously  determined  by  measure- 
ment that  central  incisors  and  cuspids  of  a  size  suitable  to  fill  the  space 
would  be  more  proportionate  than  if  the  size  of  these  teeth  haa  been 
sufficiently  reduced  to  make  accommodation  for  four  incisors.  In  other 
words,  two  teeth  of  proportionate  size  would  look  better  than  foui  small 
ones. 

The  results  obtained,  as  illustrated  in  Fig.  484,  wrought  a  most 
wonderul  improvement  in  the  features  of  the  patient,  and  when  this 
consideration  is  combined  with  the  fact  that  absolutely  no  gold  was  visible 
anywhere  anterior  to  the  sixth-year  molars,  and  that  the  patient  carries 
with  her  a  duplicate  crown  for  every  tooth  (Fig.  485),  excepting  the  two 
jacket  crowns  on  the  lower  incisors,  numbered  also  on  a  record  chart 
which  is  given  to  the  patient,  so  that  any  dentist  anywhere  may  readily 
and  easily  take  care  of  her  in  case  of  accident  or  emergency,  it  is  ap- 
parent that  such  results  approach  closely  to  the  ideal,  and  indicate  and 
emphasize  the  possibilities  of  modern  methods. 

The  object  of  placing  a  number  on  each  duplicate  tooth,  and  also 
giving  the  patient  a  chart  similarly  numbered,  is  to  enable  any  dentist 


575 


FL^M 


FIQ,  S. 


57^ 

to  whom  the  patient  might  be  obliged  to  apply  in  an  emergency,  to  be 
able  to  identify  the  duplicate  for  the  one  that  may  have  been  broken. 
Thus  the  duplicates  in  the  above  case  were  numbered  in  the  order  in 
which  the  originals  were  used,  and  these  numbered  duplicates  were  given 
to  the  patient.  A  regular  chart,  such  as  is  commonly  used  in  dental 
account  books,  was  then  numbered  similarly,  and  also  given  to  the 
patient.  Thus  any  dentist  called  upon  to  replace,  let  us  say  the  left  upper 
cuspid,  by  consulting  the  chart  would  note  that  such  tooth  was  numbered 
"6,"  and  he  would  then  use  duplicate  number  "6"  in  making  the  repair. 
This  method  of  giving  the  patient  accurately  numbered  duplicates, 
and  a  similarly  numbered  chart,  is  quite  advantageous  where  many  teeth 
are  placed  in  one  mouth,  for  it  must  be  remembered  that  there  are  four 
cuspids  and  eight  bicuspids,  which,  in  many  instances,  might  be  mistaken 
the  one  for  another.  Even  molars  are  not  always  positively  recog- 
nizable. 

Smaller  Cases. 

Further  evidence  of  the  value  of  the  casting  process,  as  applied  to 
the  construction  of  "fixed"  bridgework,  of  a  more  or  less  typical  char- 
acter, and  in  which  inlays  are  used  as  attachments,  is  illustrated  in  the 
following  cases : 

Plate  D,  Fig.  i,  shows  the  application  of  inlays  involving  only  the 
lingual  surfaces  of  the  central  incisor  and  cuspid,  without  devitalizing  the 
pulp,  and  which  are  used  to  support  a  missing  lateral  incisor. 

This  particular  type  of  cavity  preparation  is  adapted  more  generally 
to  those  cases  where  the  supporting  teeth  have  pronounced  "bell-shape" 
crowns,  where  large  interproximal  spaces  admit  of  keeping  their  approx- 
imal  surfaces  clean,  and  where  the  conservation  of  the  pulp  is  desired. 
The  use  of  small  pins,  however,  is  regarded  as  being  essential  to  the  se- 
cure fixation  of  this  type  of  anchorage. 

Plate  D,  Fig.  2,  shows  the  application  of  inlays  with  large  posts  ex- 
tending well  into  the  canals  of  teeth  which  have  been  devitalized,  and  in 
which  the  cavity  preparation  has  been  made  to  involve  the  approximal 
surfaces  of  each  tooth,  thereby  bringing  the  margins  of  the  inlay  to  im- 
mune or  self-cleansing  areas.  This  type  of  cavity  preparation  is  gene- 
rally regarded  as  being  the  best  practice,  wherever  more  than  one  tooth  is 
to  be  supplied,  and  devitalization  is  possible. 

It  will  also  be  observed  that  the  extent  of  abso/ption  in  this  case  de- 
manded considerable  restoration,  and  that  this  was  obtained  by  making 
a  gum  block  of  two  separable  dowel  crowns,  and  subsequently  cement- 
ing them  to  the  cast  saddle  after  it  had  been  soldered  to  the  inlays.    Such 


577 


FIG.    I. 


FIG.  2. 
PLATE  E 


578 

blocks  may  be  easily  made  by  selecting-  and  grinding  the  crowns,  burnish- 
ing platinum  foil  to  the  model,  filling  in  between  the  crowns  and  the  foil 
with  high  fusing  body,  and  subsequently  finishing  with  gum  enamel. 

Plate  D,  Fig.  3,  illustrates  a  more  extensive  case  of  the  same  kind, 
but  in  which  ordinary  long-pin,  flat-back  facings  were  used  in  making  the 
gum  block.  The  making  of  the  block,  with  provision  for  its  subsequent 
attachment  to  the  supporting  inlays,  was  accomplished  by  first  soldering 
the  facings  to  a  round  iridio-platinum  wire,  14  gauge,  bent  to  fit  around 
the  curvature  of  the  teeth,  immediately  under  the  pins,  and  with  each  end 
flattened  and  adapted  to  a  close  contact  with  the  inlays.  When  so  assem- 
bled, platinum  foil  was  then  burnished  to  the  model,  and  the  desired 
restoration  built  up  with  porcelain  body.  When  the  block  was  completed, 
it  was  placed  in  position  on  the  model  and  invested,  and  the  projecting, 
flattened  ends  of  the  iridio-platinum  wire  were  then  soldered  to  the  inlays 
with  22-karat  solder. 

Plate  E,  Fig.  i,  illustrates  a  t3'pical  method  of  supplying  a  missing 
sixth-year  molar,  where  the  cosmetic  requirements  call  for  the  use  of  a 
full-size  tooth,  such  as  is  usually  demanded  in  the  upper  arch,  and  where 
a  Davis  or  other  separable  dowel  crown  with  a  cast  backing  will  afford 
the  strongest  and  most  artistic  results  possible.  The  same  type  of  con- 
struction is  also  applicable  to  cases  where  two  or  even  three  teeth  are 
demanded. 

Plate  E,  Fig.  2,  illustrates  the  same  type  of  work  applied  to  the  lower 
jaw,  where  the  cosmetic  requirements  are  not  so  great,  and  where  the 
restoration  of  the  occlusal  surface  is  all  that  is  demanded. 

This  type  of  construction  is  generally  applicable  to  one  or  more 
teeth  in  the  lower  arch,  wherever  the  extent  of  absorption  is  sufficient 
to  allow  ample  opportunity  for  keeping  all  surfaces  clean,  and  where  the 
display  of  gold  occlusal  surfaces  is  not  conspicuous  or  objectionable. 


Remc'vable  Briagework  and  Partial  Dentures. 

CHAPTER  XXX. 


Indications.      Anchorage    or    Attachments :    Use    of    Clasps,    Typical    Application, 
Vulcanite  Bases,  Gold  Bases,  Cast  Clasps,  Clasping  Porcelain  Crowns,  Clasp- 
ing Natural  Crowns.   Use  of    Roach    Attachments :  In  Connection  with 
Inlays,     In     Connection    with    Porcelain     Crowns,     Precautions. 
Construction    of    Fixtures :     Small    Cases,    Investing    and 
Casting.      Larger    Cases:    Extension    Bar    Bridges, 
Overcoming     Simple     Difficulties,     Assembled 
Abutment    Pieces.      Removable    Attach- 
ments     in      Comliination      with 
Porcelain. 


Whatever  the  casting  process  may  have  done  in  the  way  of  revolu- 
tionizing and  simpHfying  the  methods  of  procedure  formerly  observed  in 
the  filling  of  teeth,  and  in  the  construction  of  single  crowns  and  fixed 
bridges,  and  however  applicable  it  may  be  to  this  line  of  work,  it  is  also 
equally  applicable  to  and  especially  valuable  and  useful  in  the  construc- 
tion of  removable  bridgework,  and  all  forms  of  partial  dentures — where 
the  same  accuracy  of  adaptation  and  the  same  requirements  of  strength 
are  demanded,  and  where  the  fixtures  are  usually  and  necessarily  larger. 

While  no  class  of  work  will,  perhaps,  ever  take  the  place  of  well- 
adapted  and  properly  constructed  "fixed"  bridgework,  or  answer  the  same 
purposes,  yet,  since  the  success  of  such  work  primarily  depends  entirely 
upon  the  favorable  location  and  stability  of  the  supporting  teeth  or  roots, 
some  form  of  removable  structures  will  always  be  indicated  in  that  large 
percentage  of  cases  where  these  combined  essentials  do  not  present. 

Hence,  "fixed"  bridgework  is  indicated  only  in 

indications.  those  cases  where  the  position  and  stability  of  the 

supporting  teeth  are  favorable,  while  in  all  cases 
where  these  primary  requirements  do  not  present,  removable  structures 
are  not  only  indicated^  but  demanded. 


58o 

The  successful  application  of  removal  structures,  while  not  depend- 
ing so  much  upon  the  favorable  position  or  location  of  the  supporting 
teeth  in  the  arch — for  the  reason  that  much  of  the  stability  of  the  struc- 
ture is  assumed  by  contact  of  the  base  of  the  piece  with  the  contiguous 
soft  tissues — will  necessarily  depend  largely  upon  the  manner  in  which 
fixation,  attachment  or  anchorage  to  the  supporting  teeth  is  obtained. 

Thus  the  application  of  removable  structures  which  are  sustained  by 
some  mechanical  means,  instead  of  by  simple  contact  with  the  soft  tissues, 
such  as  a  so-called  partial  "plate,"  resolves  itself  largely,  first,  into 
a  question  of  anchorage  to  the  remaining  or  supporting  teeth,  and, 
second,  into  the  best  method  of  obtaining  the  required  accuracy  of  adapta- 
tion and  strength  in  the  construction  of  the  fixtures ;  in  both  of  which 
instances  the  casting  process  affords  an  almost  unlimited  range  of  appli- 
cation and  a  wide  field  of  possibilities. 


Jfttcborage  or  Jlttacbmettts. 

The  question  of  the  best  or  most  universally  applicable  means  of 
obtaming  anchorage  for  removable  structures  of  any  type  is  one  which 
will  probably  always  depend  much  upon  personal  equation  or  individual 
preference,  but  while  the  casting  process  is  alike  applicable  to  any  and  all 
of  the  various  forms  of  attachments,  it  is  particularly  applicable  to  the 
construction  and  use  of  clasps  of  various  forms,  and  to  the  use  of  the 
"Roach,"  "Morgan,"  of  any  of  the  other  similar  designs  now  manufac- 
tured for  this  purpose ;  and  these  two  general  types  of  anchorage  afford  a 
very  wide  range  of  application  and  general  usefulness  when  combined 
v/ith  the  facilities  and  advantages  now  offered  by  the  casting  process. 

As  applied    to  molars  and  bicuspids,  clasps  must 
U$t  OT  €la$P$.  always   be  regarded   as   a  most   useful   and  reliable 

means  of  obtaining  attachment  for  the  anchorage  of 
all  forms  of  removable  bridges  or  partial  dentures.  When  their  use  is 
confined  to  these  teeth,  when  they  are  of  favorable  shape  and  position  in 
the  arch,  and  when  they  are  made  in  accordance  with  the  general  require- 
ments of  a  clasp,  as  previously  detailed,  and  made  of  an  alloy  possessing 
toughness  and  resiliency — such  as  rolled  or  "plate"  clasp-metal,"  and 
properly  adapted  to  the  supporting  tooth,  with  an  adequate  provision 
against  the  possibility  of  subsequent  settlement,  they  afford,  perhaps,  the 
most  simple,  secure,  permanent  and  universally  applicable  means  of 
obtaining  attachment  to  these  particular  teeth,  which  is  now  at  our 
command. 


58i 

It  must  be  remembered,  however,  that  because  of  the  injury  to  the 
natural  crowns  of  teeth  likely  to  result  from  the  influences  of  mechanical 
abrasion  or  attrition,  the  best  and  most  permanent  results  are  to  be 
obtained  by  first  placing  artificial  crowns  upon  the  roots  of  the  supporting 
teeth,  and  adapting  the  clasps  to  them.  Such  crowns  may  be  made  of 
gold,  or  of  porcelain  if  the  cosmetic  requirements  demand,  but  it  should 
always  be  observed  that  the  shape  given  to  them  is  made  favorable  to  the 
subsequent  adaptation  of  the  clasp, 

An  occlusal  rest  or  some  other  means  of  preventing  any  great  de- 
gree of  subsequent  settlement  in  the  mouth,  however  must  always  be 
observed,  for  if  such  provision  is  not  made,  the  case  will  continue  to  settle 
as  absorption  progresses,  with  the  result  that  the  occlusal  relationship  and 
usefulness  of  the  piece  may  be  destroyed,  and  much  discomfiture  and 


Fig.  487 


injury  to  the  soft  tissues  surrounding  the  supporting  teeth  may  be  caused 
by  impingement  of  the  clasps  upon  them. 

Perhaps  the  most  simple,  practical  and  useful 
typical  flppSication.  application  of  clasps  to  gold  crowns  may  be  made 
by  making  the  crown  with  straight  or  parallel  sides 
and  cutting  a  seat  in  the  occlusal  surface  of  the  wax  of  proportions 
sufficient  to  accommodate  an  occlusal  rest,  just  before  investing  and 
casting  (Fig.  486). 

When  the  crown  has  been  cast  (Fig.  48 7)  it  should  then  be  finished 
and  mounted.  The  clasp  should  now  be  made  of  26-gauge  clasp-metal 
and  trimmed  and  adapted  to  the  crown  directly  in  the  mouth,  after  which 
a  plaster  impression  should  be  taken  with  the  clasp,  or  clasps,  in  place, 
and  the  model  made  after  carefully  ascertaining  that  the  clasp  occupies 
its  proper  position  in  the  impression.  If  the  case  is  to  be  made  of 
vulcanite,    the    model    may    be    of   plaster,   but    if   the   clasp    is    to   be 


582 

attached  to  a  gold  or  platinum  base  by  means  oi  soldering,  the  model 
should  be  made  of  investment  material. 

Where  vulcanite  is  to  be  used  as  a  base,  the 
UtllcaniU  Bases.         clasp  should  first  be  detached  from  the  model,  exer- 
cising care  so  as  not  to  break  off  the  plaster  tooth  sup- 
porting it,  and  when  thus  loosened  and  then  readjusted  to  place,  a  piece 
of  17  or  18  gauge  round  iridio-platinum  wire  should  be  adapted  to  the 
broad  surface  of  the  clasp  with  the  occlusal  end  bent  at  a  right  angle  and 


Fiii.  488 


Figf.  489 


Fig.  490 


Fig.  491 


fitted  into  the  seat  in  the  plaster  tooth,  corresponding  to  the  same  accom- 
modation in  the  crown,  and  the  other  end  formed  into  a  loop  of  suitable 
size  to  insure  secure  attachment  to  the  vulcanite  (Fig.  4<S8). 

When  so  fitted  the  desired  relation  of  the  wire  to  the  clasp  should 
be  sustained  with  hard  wax,  the  whole  gently  lifted  ofl^  of  the  model,  in- 
vested and  soldered,  after  which  it  may  be  replaced  upon  the  model 
(Fig.  489),  and  the  case  completed  in  the  usual  manner. 

Where  a  gold  base  is  used,  the  base  should  be 

Cold  Bases.  made  as  soon  as  the  investment  material  model,  with 

the  clasp  in  place,  has  been  obtained.    A  piece  of  17- 
or   i8-gauge  round  iridio-platinum  wire  should  then  be  bent  and  fitted^ 


583 

into  the  seat,  and  to  a  close  contact  with  the  flat  surface  of  the  clasp,  and 
to  the  surface  of  the  gold  base  (Fig.  490)-  It  may  then  be  soldered  to 
both  directly  upon  the  model  (Fig.  491). 

A  typical  case  showing  the  application  of  clasps  to  gold  crowns  on 
the  two  lower  second  bicuspids  is  illustrated  in  Fig.  492. 

Another  very  useful  application  of  clasps  to  gold  crowns  is  to  be 
obtained  by  first  making  the  crown  with  a  narrow  band,  and  forming  and 
shaping  it  to  meet  the  other  requirements  with  wax,  after  which  a  shoul- 
der should  be  trimmed  away  in  the  wax  to  follow  and  accommodate  the 
desired  outline  and  form  of  the  clasp.  The  crown  should  then  be  in- 
vested and  cast,  after  which  26-gauge  clasp-metal  may  be  fitted  to  place 
on  the  crown,  and  subsequently  attached  to  the  base  in  the  manner  indi- 
cated above.  Or  the  clasp  may  first  be  made  in  wax  to  fit  the  groove  in 
the  crown,  and  this  subsequently  cast   (Fig,  493). 


Fig.  492 


Fig.  493 


The  casting  of  clasps,   however,   is  not  recom- 
Ca$t  €Ia$p$.  mended,  for  the  reason  that  even  though  clasp-metal 

be  used  for  the  purpose,  the  process  of  casting  it 
seems  to  completely  destroy  its  resiliency— the  very  quality  which  a  clasp 
Dinst  possess — and  causes  it  to  become  very  brittle.  Hence,  clasps  or  any 
other  parts  where  toughness,  strength  and  springiness  are  demanded 
should  always  be  made  of  rolled  clasp-metal  alloy. 


5S4 

These  same  principles  are  equally  applicable  to 
Clasping  Porcelain       the  adaptation  of  clasps  to  porcelain  crowns   in  all 
Crowns,  cases  where  porcelain  is  demanded  for  cosmetic  rea- 

sons,  and   where   the   crown   may   be   so   shaped  or 
ground  as  to  afford  similar  opportunity. 

Wherever  the  adaptation  of  the  clasp  directly  to 

Clasping  natural        the  natural  crown  of  a  tooth  may  seem  to  be  indi- 

Crowns.  cated    or   warrantable — which   is    not   often,   except, 

perhaps   in   old   age — the    same    general    principles 

should  always  be  observed,  and  in  cases  where  the  placing  of  an  occlusal 

rest,  as  indicated,  may  interfere  with  the  occlusion,  the  tooth  to  be  clasped 

should  be  ground  until  suitable  accommodation  is  thereby  obtained. 


Use  of  "Roacb"  JIttacDmenfs. 

If  clasps  are  especially  applicable  to  the  molar  teeth,  and  occasionally 
to  the  bicuspids,  and  particularly  when  they  may  be  used  in  connection 
with  gold  crowns,  the  ball  and  telescoping  tube  attachments  designed 
by  Dr.  F.  E.  Roach  are  ec[ually  applicable  and  useful  as  applied  to  the 
ten  anterior  teeth,  and  especially  to  the  six  anterior  teeth,  where  they  may 
be  used  in  connection  with  inlays  or  porcelain  crowns,  and  where  clasps  of 
any  form  are  impracticable,  owing  to  the  unfavorable  shape  of  these 
teeth. 

While  the  two  parts  may  be  interchangeably  used,  it  is  usually  best 
to  attach  the  ball  to  the  supporting  tooth  and  the  tube  to  the  removable 
part  of  the  fixture,  as  this  procedure  more  readily  admits  of  subsequent 
tightening  in  the  event  of  wearing  loose,  which  contingency  is  more  or 
less  inevitable. 

When  it  is  desirable  to  use  the  Roach  attachment 
Tn  Connection  with       in  connection  with  an  inlay,  the  cavity  must  be  pre- 
Tnlays.  pared  so  that  the  inlay  will  involve  or  include  sufifi- 

cient  surface  and  thickness  to  admit  of  placing  the 
ball  part  of  the  attachment  in  the  most  favorable  position  to  afford  secure 
attachment,  and  at  the  same  time  offer  opportunity  for  the  proper  adjust- 
ment of  the  adjacent  artificial  tooth  to  be  supplied,  which  always  demands 
that  it  be  placed  zvell  to  the  lingual  surface,  and  all  inlays  used  to  support 
this  or  any  other  type  of  attachment  for  removable  work  must  have  one 
or  more  pins  in  them. 

When  the  cavity  has  been  so  formed  and  the  wax  filling  made^  about 
one-half  of  the  shank  projecting  from  the  ball  should  usually  be  cut  off, 


585 

the  remaining  end  then  grooved  or  roughened,  the  baU  grasped  with  small 
pliers,  slightly  heated,  and  the  small  surplus  end  then  forced  into  the  wax 
filling  to  the  proper  depth,  and  at  the  proper  point.  After  observing  that 
this  attachment  to  the  wax  has  been  made  secure,  the  sprue-wire  should 
then  be  likewise  attached  at  a  favorable  point  (Fig.  494  A),  and  the  filling 
then  invested  and  cast   (Fig.   494  B). 

By  this  means  the  attachment  becomes  an  integral  part  of  the  filling 
and  its  position  in  relation  to  the  filling,  together  with  a  greater  degree 
of  strength  than  is  usually  obtained  by  soldering,  is  facilitated  and  insured. 


a  b 

Fis  494 


Fig.  495  Fig.  49b 

Where  the  attachment  is  to  be  used  in  connec- 
Tn  Connection  ^^°"  '^^^^'^  porcelain  crowns  with  cast  bases,  such  as 

Uijtl)  are  indicated  and  now  more  or  less  generally  used 

Porcelain  Crowns.  in  restoring  the  ten  anterior  teeth,  a  narrow,  well- 
adapted  band  sliould  invariably  be  used,  and  the 
lingual  or  approximal  surfaces  of  the  porcelain  tooth  or  crown  must  be  so 
ground  as  to  afford  sufficient  space  between  it  and  the  root  to  allow  of  a 
thickness  of  wax  which  will  accommodate  the  attachment  of  the  ball  at 
the  proper  point.  This  part  of  the  attachment  should  now  be  prepared 
(as  indicated  for  inlays),  and  then  securely  attached  to  the  wax  while 
the  crown  is  in  position,  after  which  the  sprue-wire  may  be  attached,  the 
porcelain  removed  (Fig.  49S).  ^"d  the  base  invested  and  cast  (Fig.  49'^). 

In    thus   casting    directly   to    the   attachment   it 

Precautions.  must  be  observed    that    the    end    is    first    properly 

notched  or  roughened  and  then  that  it  is  forced  or 

buried  into  the  wax  to  an  extent  which  will  insure  strength  in  the  sub- 


586 

sequent  union  of  the  attachment  and  gold  used  in  casting.  It  is  also  well 
to  paint  with  whiting  the  surface  of  the  ball  up  to  and  including  the 
slight  groove  into  which  the  tube  fits  before  investing,  as  such  a  precau- 
tion precludes  the  possibility  of  increasing  the  size  of  the  ball  by  the  addi- 
tion of  any  of  the  metal  used  in  casting,  or  of  fusing  it  during  this 
process,  both  of  which  may  and  sometimes  do  happen. 


Fig.  497 


A  combination  of  "Roach  attachments"  applied  in  this  mariner  to  the 
anterior  teeth  which  are  to  be  used  as  supports,  or  even  where  the  shank 
of  the  ball  is  cemented  directly  into  the  tooth  without  either  inlay  or 
crown,  or  where,  for  any  reason,  it  may  be  used  in  connection  with  a  gold 
crown,  or  even  with  an  "open-face"  crown,  and  of  "clasps"  applied  to 
the  posterior  teeth  seems  to  offer  a  range  of  application  well-adapted  to 
meet  all  of  the  requirements  of  removable  bridgework. 

A  typical  application  of  these  attachments  where  porcelain  crowns  are 
used  on  the  lower  first  bicuspids  is  illustrated  in  Fig.  497,  and  in  connec- 
tion with  large  inlays,  or  so-called  "Carmichael"  attachments  with  a  post 
of  generous  size  in  each,  as  applied  to  lower  cuspids,  is  shown  in 
Fig.  498 

Another  typical  case,  showing  the  application  of  a  Roach  attachment 
to  a  molar  crown  on  one  side,  and  of  a  clasp  to  a  bicuspid  crown  on  the 
opposite  side,  as  a  means  of  supporting  the  missing  bicuspids  and  molars 
on  one  side  of  the  arch  only,  is  illustrated  in  Fig.  507. 

The  telescoping  tube  and  split-post  attachment  is 
useful  when  applied  to  the  roots  of  the  six  anterior 
teeth,  or  where  tlie  tube  may  be  buried  witliin  the 
tootli.  anrl  without  a  too  liberal  sacrifice  of  tooth 
structure. 


telescoping  tube 

and 

Split-Post. 


587 

The  Roach,  Morgan  and  other  types  of  manu- 

IHanufactured        factured  attachments  will  also  be  found  valuable 

JTttacbmcittS.        when  used  in  connection  with,  and  projecting  from, 

either  porcelain   or  gold   crowns,   or  gold   inlays, 

on  the  cuspids  and  bicuspids. 

In  addition  to  these,  I  am  pleased  to  subm.it  a 

J\  Hew  method  of  attachment  which,  while  perhaps  but  a 

flttacbmcnt.  modification  of  some  of  the  previously  mentioned 

types,  is  entirely  new  and,  more  or  less,  universally 

applicable. 


Fi{f   499 

This  attachment  consists  in  utilizing  the  grasping  principle  of  an 
open  tube  with  straight  and  parallel  sides,  which  is  the  removable  part 
of  the  fixture,  in  combination  with  a  round  wire,  of  about  12  gauge, 
attached  to  and  therefore  a  part  of  the  "fixed"  portion  of  the  structure, 
but  lying  in  a  Jiorizontal  position  instead  of  in  a  vertical  one.  in  its 
relation  to  the  supporting  fixture. 

Such  an  attachment  may  be  made  by  utilizing  the  tube  of  a 
"Roach''  attachment  in  comliination  with  12-gauge  clasp-metal  wire, 
and  while  simple  and  easily  constructed  is  especially  useful  in  exten- 
sive cases,  where  the  abutment  ])ieces  are  assemliled,  though  equally 
applicable  to  less  extensi\'e,  or  to  the  most  simple  cases.  (Figs.  499 
and  500.) 

It  is  easily  applied,  easily  tightened  when  loosened  by  wear,  takes 
up  but  little  space,  does  not  require  absolute  parallelism  when  more 
than  one  is  used  on  the  same  fixture,  is  applicable  alike  to  either  gold 
or  vulcanite  work,  and  is  secure. 


588 

The  conception  of  this  attachment  on  my  part  was  forced  upon 
me  in  a  very  interesting  manner.  About  a  year  and  a  half  ago  I  in- 
serted a  large  fixture  in  the  upper  jaw,  involving  the  six  anterior  teeth 
and  the  two  third  molars,  the  latter  being  joined  to  the  former  with  an 
iridio-platinum  wire,  12  gauge,  resting  upon  the  summit  of  the  ridge 
on  each  side.  In  about  the  center  of  the  wire  on  both  sides  a  vertical 
split-post  was  attached.  This  constituted  the  fixed  structure,  which 
was  cemented  to  place,  the  split  posts  supporting  a  removable  saddle, 
which  supplies  the  bicuspids  and  molars. 


Fig.  500 

A  few  weeks  after  the  completion  of  the  case  the  patient  returned 
with  one  of  these  split-posts  broken  away  from  the  fixture,  leaving 
nothing  to  hold  that  side  in  place.  At  first  this  seemed  a  calamity, 
which  meant  only  the  destruction  and  removal  of  the  fixture,  and  the 
making  over  of  the  entire  case.  As  this  was  not  a  particularly  pleas- 
ant procedure  to  anticipate,  and  as  necessity  has  always  exercised  a 
maternal  influence  upon  the  possible  inventive  ingenuity  of  man,  it 
occurred  to  me  that  T  might  obtain  attachment  to  that  wire  by  grasp- 
ing it  with  an  open  cylinder,  or  tube,  lying  parallel  with  it,  and  thus 
avoid  removing  and  rebuilding  the  whole  appliance.  This  I  did,  with 
the  re.'uilt  that  this  side  workerl  so  well,  and  seemed  so  much  stronger 
than  the  one  where  the  vertical  split-post  remained,  that  I  subse- 
fjucntly  ground  it  olT  and  used  the  open  tube  on  that  side  also,  and 
the  utilization  of  this  form  of  attachment  in  many  cases  since  then  has 
given  me  more  satisfaction  than  I  have  ever  obtained  from  any  other 
method. 


589 

In   the  application   of  this   attachment   in   all 

technique.  cases  where  the  supporting  wire  extended  distally 

from  the  fixed  portion  of  the  structure,  and  where 

it  lies  on  the  summit  of,  and  parallel  with,  the  ridge,  it  is  essentially 

necessary  that  it  should  be  supplied  with  a  "head,"  which  will  prevent 

any  slipping  or  sliding  of  the  removable  structure.     (Fig.  501.) 

If  such  a  provision  is  not  made  some  movement  and  loss  of 
stability  will  result  from  the  stress  of  mastication.  But  when  this  wire 
is  placed  at  an  angle,  or  projects  toward  the  center  of  the  plate,  such 
provision  is  not  necessary.     (Fig.  5  shows  both  styles.) 


Fig.  501  Fig.  502 


When  used  in  connection  with  gold  saddles. 
Gold  Saddles.  the  fixed  portion  of  the  structure,  including  the 
wire  extensions,  should  be  completed  and  cemented 
to  position  on  the  supporting  teeth.  When  firmly  and  securely  at- 
tached, the  open  tubes  should  then  be  placed  in  position  in  their 
proper  relation  to  the  wire  extensions,  and  a  bite,  in  wax,  and  impres- 
sion in  plaster  then  taken. 

AAHien  the  impression  has  been  removed  the  tubes  should  be 
detached  from  the  wire  and  placed  in  position  in  the  impression,  and 
held  securely  therein  with  a  bit  of  melted  wax  if  necessary. 

A  "dummy"  Avire  of  German  silver,  which  should  be  a  counterpart 
of  the  original,  though  somewhat  longer,  should  now  be  fitted  into  the 
tubes  as  they  lay  in  the  impression,  and  the  latter  then  varnished  and 
filled  with  a  good  soldering  investment  material.  The  presence  of  the 
"dummy"  German  silver  wires  causes  the  tubes  to  be  held  securely  in 
position  on  the  model  when  separated  from  the  impression. 

\Mien  the  saddles  are  to  be  made  by  the  cast- 
Cast  Saddles.         i'l^i'  pi'ocess,  as   soon  as  the  model   has  been  ob- 
tained, each  of  the  open  tubes  should  be  carefully 
detached  and  a  small  piece  of  round,  iridio-platinum  or  clasp-metal 
wire  of  about  17  gauge,  just  long  enough  to  project  slightly  beyond 
the  tube  at  each  end,  soldered  to  the  center  of  the  tube.     (Fig.  502.) 


590 

Place  the  tubes  back  in  position  on  the  model,  then  varnish  over  the 
entire  surface  well  in  order  to  facilitate  the  removal  of  the  wax  pattern. 


Fiff.  503 


and  then  mold  very  thin  wax  to  the  desired  outline  of  the  saddle,  and  cut 
out  the  wax  to  expose  the  wires  on  the  tubes.  This  will  leave  a  hole  in 
the  wax  saddle  through  which  each  wire  will  be  exposed. 

Now  stiffen  and  otherwise  perfect  the  wax  pattern;  then  adjust  the 
sprue  formers — remove,  invest  and  cast,  using  coin  gold.  The  wax  sad- 
dle, or  pattern,  may  be  stiffened  with  a  bead  of  very  hard  wax,  or  any 


591 

change  of  form  may  be  overcome  by  covering  it  with  a  thin  coating  of 
casting  investment  material  before  removing  it  from  the  model,  and  after 
the  sprue  formers  have  been  attached.  When  the  casting  has  been  made, 
the  opening  through  it  should  be  trimmed  until,  when  fitted  to  position 
over  the  model,  the  wire  on  the  open  tube  will  project  through. 

The  relation  between  the  saddle  and  tube,  with  its  wire  lug  projecting 
through,  should  now  be  securely  sustained  with  hard  wax,  removed  from 


Fig.  504 


the  model,  invested,  and  soldered,  after  which  the  piece  may  be  again 
placed  on  the  original  model,  and  if  to  be  joined  with  each  other  by  means 
of  a  palatal  strip,  if  in  the  upper  jaw  (as  illustrated  in  a  typical  case  in 
Fig.  503),  or  a  lingual  wire,  if  the  lower  jaw  (Fig.  504),  these  should  now 
be  fitted,  and  the  attachment  of  all  parts  then  made  by  soldering  directly 
on  the  model. 

After  the  substructure  has  been  thus  completed,  it  should  be  placed 
in  position  in  the  mouth,  and  a  bite  in  wax  and  impression  in  plaster  then 
taken,  after  which  the  teeth  may  be  arranged  and  the  removable  part  com- 
pleted in  the  usual  manner. 

In  the  construction  of  cast  bases,  if  a  good  model  of  a  high-grade  in- 
vestment material  is  obtained,  and  if  the  wax  base  is  carefully  formed, 
made  sufficiently  thin  and  properly  stiffened,  the  process  offers  every 
assurance  of  accuracy  of  adaptation  and  of  strength,  and  the  possibilities 
are  unlimited.  For  all  forms  and  sizes  of  saddles,  or  bases,  coin  gold 
seems  to  be  especially  adapted  to  cast  work,  and  to  afford  all  of  the  in- 
tegral strength  ordinarily  demanded. 


592 

While   this   attachment   is   equally   useful   when 

UulCSnitC  lUork.        confined  to  simple  vulcanite  cases,  still  to  have  the 

best  results  the  open  tube  should  be  attached  to  a 

palatal  bar,,  or  lingual  wire,  with  solder,  wherever  possible,  as  illustrated 

in  a  typical  upper  case  in  Fig.  505. 


Fig    505 


When  used  in  this  manner  the  proper  position  is  securely  sustained, 
and  the  saddles  and  attachment  of  the  teeth  may  then  be  made  with  vul- 
canite. 


Fig.  r,oo 

In  this  procedure  the  technique  is  the  same  as  previously  described. 

Where  the  case  is  to  be  made  entirely  of  vulcanite,  however,  the  open 
tubes  should  be  placed  in  position  in  the  mouth  and  the  bite  and  impres- 
sion taken. 

When  the  model  has  been  obtained  and  mounted  upon  the  articulator, 
the  open  tubes  should  be  removed,  and  a  piece  of  i6-guage  iridio-platinum 
or  clasp-metal  wire,  slightly  flattened,  and  with  each  projecting  end  bent 
away  from  the  open  tube  and  notched,  should  be  securely  soldered  to  the 
center  of  the  tubes.     TFig.  506.) 


593 

Each  of  the  open  tubes  should  then  he  mounted  to  position  on  the 
model  with  cement,  allowing  a  slight  surplus  to  remain. 

When  this  has  been  hardened,  the  relation  will  be  securely  sustained, 
after  which  the  case  should  be  completed  in  the  usual  manner  as  for  any 
vulcanite  work. 

A  similar  attachment,  known  as  Gilmore's,  is  now  being  manufac- 
tured, and  may  be  easily  obtained  by  those  who  do  not  care  to  make  their 
own. 

Construction  of  fixtures. 

When  the  type  and  number  of  attachments  which  are  to  be  used  for 
the  purpose  of  anchoring  removable  bridges  or  partial  dentures  to  the 
remaining  natural  teeth  have  been  determined,  and  each  attachment  has 
first  been  made  separately,  it  then  becomes  necessary  to  decide  how  the 
body  of  the  structure  which  is  to  support  the  artificial  teeth  shall  be  con- 
structed. 

While  vulcanite  alone  may  be  used  for  this  purpose,  economy  is  the 
one  and  only  advantage  to  be  derived  from  its  use,  and  the  best  results, 
from  the  viewpoints  of  both  strength  and  hygiene,  are  to  be  obtained  by 
the  use  of  gold,  either  in  combination  with  vulcanite  or  alone,  or  of 
platinum  in  combination  with  porcelain. 

In  the  casting  process,  coin,  twenty-two-,  or  even  twenty-karat,  gold 
may  be  used  for  the  structure,  and  the  artificial  teeth  subsequently  attached 
thereto  with  vulcanite.  This  is  probably  the  most  typical  type  of  con- 
struction. In  cases  wdiere  any  considerable  amount  of  restoration  is  not 
demanded,  however,  ordinary  replaceable  porcelain  crowns,  bridge  teeth, 
vulcanite,  or  diatoric  teeth  may  be  used  by  first  molding  the  wax  to  the 
model  and  to  the  teeth,  and  then  casting  the  entire  body  of  the  structure 
and  subsequently  cementing  the  teeth  to  this,  thus  using  no  vulcanite  and 
avoiding  the  danger  of  casting  directly  to  the  porcelain.  Or,  where  con- 
siderable restoration  is  demanded,  and  where  the  cosmetic  requirements  in- 
dicate porcelain,  an  alloy  of  five  or  ten  per  cent,  of  platinum  in  pure  gold 
may  be  used  in  casting  the  base,  and  the  teeth  afterward  soldered  to  this 
with  pure  gold.  The  restoration  may  then  be  made  with  low-fusing 
bodies  and  gum  enamels,  being  sure  to  use  those  which  fuse  below  the 
melting-point  of  pure  gold,  such  as  Jenkins'  "Prosthetic,"  Brewster's,  etc. 

Perhaps  the  most  simple,  typical  and  universally 

Small  €a$($.  applicable  type  of  construction  is  indicated  in  supply- 

ing teeth  on  one  side  of  the  arch  only  (Fig.  507),  or 
in  small  anterior  ca.ses  (Fig.  50S),  and  consists  in  making  a  gold  saddle 


594 

and  attaching  the  artificial  teeth  to  it  by  means  of  vulcanite,  which  may 
be  done  by  casting,  with  accuracy  and  facility,  without  dies,  counter-dies 
or  swaging,  and  with  a  degree  of  certainty  measured  only  by  the  operator's 
skill. 


Fit'.  507 


In  this  procedure  the  completed  crowns  or  inlays,  together  with  the 
removable  parts  of  the  attachments  used  therewith,  should  be  placed  in 
position  in  the  mouth,  and  a  good  impression  obtained  in  plaster  and  a 
model  then  made  of  a  good,  smooth  investment  compound.     When  the 


[p|||PliMlli 


Fig.  508 


latter,  with  the  attachments  in  place,  has  been  obtained,  it  should  first  be 
properly  treated  to  prevent  the  wax  from  sticking  to  it.  Varnishing  with 
shellac  and  then  with  sandarac,  and,  when  these  have  dried  thoroughly, 
with  glycerine  or  thin  oil,  will  usually  answer  this  purpose  nicely.  Or, 
as  a  means  of  affording  a  close  adaptation  and  a  smooth  surface,  and  pre- 


595 

venting  the  wax  from  adhering  to  the  model,  No.  4  gold-foil  may  first  be 
trimmed  and  burnished  over  the  working  surface,  and  this  subsequently 
invested  with  wax. 

The  wax  saddh  or  base  should  now  be  formed  to  the  model  and 
trimmed  to  the  desired  outline.    This  may  be  accomplished  by  using  the 


Fig.  509 


Ki;;.  510 


thinnest  possible  form  of  sheet  wax  especially  prepared  for  this  purpose, 
such  as  is  made  by  Ash  &  Sons,  or  ordinary  baseplate  wax,  rolled  out 
thinner.  The  saddle  may  also  be  made  by  first  melting  a  hard  wax,  such 
as  is  used  in  inlay  work,  in  a  spoon  or  other  suitable  vessel,  and  painting  it 
on  the  model  with  a  brush  until  the  desired  outline  and  thickness  obtains. 

In  the  use  of  the  thin  sheet  wax,  which  is  regarded  as  best,  however, 
it  is  always  well  to  stiffen  it  with  a  bead  of  melted  hard  wax  here  and 


there,  as  a  means  of  precluding  the  possibihty  of  any  change  of  form  in 
removing  the  case  from  the  model,  or  in  subsequently  investing  it. 

^^'hen  the  proper  outline  and  thickness  are  thus  obtained  by  either  of 
these  means,  provision  for  the  subsequent  attachment  of  the  vulcanite 
should  also  be  made,  either  in  the  wax  or  by  sticking  small  scraps  of  gold 
or  platinum  plate  or  wire  into  the  wax,  allowing  the  surplus  ends  to  be 
exposed.    (Fig.  509  ) 


Fig.  511 

When  all  of  these  requirements  and  precautions 

TltPCSting  and  have  been  observed,  the  case  is  now  ready  for  the 

Casting.  attachment  of  the  sprue-wire  and  for  investing  and 

casting. 

In  this  connection  the  successful  casting  of  large  pieces  depends,  first, 
upon  the  manner  in  which  the  sprue-wire  is  attached,  and  upon  the 
formation  of  a  sufficient  number  of  channels  leading  from  it  and  extending 
to  all  parts  of  the  mold,  which  procedure  is  usually  advisable  when  the 
piece  is  larger  than  for  two  teeth,  in  order  that  the  fluid  metal  may  reach 
every  part  of  the  mold  before  it  begins  to  cool ;  second,  upon  properly 
and  thoroughly  heating  up  and  burning  out  the  wax ;  and,  third,  upon  the 
use  of  as  much  surplus  metal  as  the  size  of  the  crucible  will  conveniently 
accommodate. 

If  these  precautions,  together  with  the  use  of  a  clean  ingot  of  a  good 
grade  of  metal  in  each  casting,  are  observed,  there  seems  to  be  no  limit 
to  the  size  of  the  piece  which  may  be  successfully  cast,  except,  perhaps, 
the  size  of  the  flask  and  of  the  machine  to  accommodate  it ;  and  the  per- 
centage of  failures  will  be  reduced  to  a  minimum  in  proportion  as  these 
features  of  correct  technique  and  careful  detail  are  developed,  and 
minutely  and  painstakingly  executed. 

The  method  of  attaching  the  sprue-wire  and  the  manner  of  making 
provision  for  the  formation  of  channels,  which  Is  done  with  a  small  roll 
of  wax  about  the  same  size  as  the  sprue-wire,  are  illustrated  in  Fig.  510 


597 

If  it  is  desirable  to  cast  directly  to  or  "pick  up"  the  removable  part 
of  an  attachment,  or  a  clasp,  and  thus  have  it  become  an  integral  part  of 
the  casting-,  such  parts  should  first  be  loosened  and  detached  from  the 
model,  and  a  small  extension  of  wire  or  clasp-metal  sufficient  to  insure 
strength  in  their  subsequent  attachment  to  the  casting  soldered  to  them 
with  a  high  grade  of  solder,  after  which  they  may  be  replaced  in  position 
on  the  model  and  waxed  up  and  removed  with  the  base,  prior  to  investing. 


Fig.  512 


Or,  if  it  may  seem  preferable  to  first  cast  the  base  and  subsequently 
attach  such  pieces  with  solder,  the  wax  may  be  molded  and  carved  to  fit 
closely  to  and  around  them,  as  illustrated  in  the  case  of  a  Roach  attach- 
ment in  Fig.  511.  When  the  piece  has  been  cast  (Fig.  512),  and  finished, 
the  relation  between  them  may  be  sustained  with  hard  wax,  when  the 
whole  can  be  removed  from  the  model,  invested  and  soldered  in  the 
ordinary  manner ;  or,  if  the  model  has  been  made  of  investment  material, 
the  soldering  may,  of  course,  be  done  directly  upon  it,  without  removing 
the  parts,  which  is  regarded  as  the  best  procedure. 

In  the  former  method,  however,  the  model  may  be  preserved  for  the 
subsequent  attachment  of  the  wax  "bite,"  which  should  have  been  obtained 
just  previous  to  the  taking  of  the  impression. 

Kargcr  C«s«$. 

Passing  from  the  smaller  class  of  cases  to  those  involving  a  greater 
area  of  contact  of  the  removable  piece  with  the  contiguous  soft  tissues, 
such  as  is  demanded  by  the  replacement  of  a  greater  number  of  missing 
teeth,  and  which  increases,  of  course,  in  proportion  thereto,  a  not  uncom- 
mon class,  among  others,  is  one  which  is  always  more  or  less  difHcuIt,  and 
which  involves  those  conditions  where  teeth  are  required  upon  one  side 
of  the  arch  only,  and  where  the  absence  of  any  posterior  teeth  on  that 


598 

side  would  ordinarily  admit  of  anchorage  of  but  one  end  of  the  fixture, 
which  is  usually  so  inadequate  as  to  be  impracticable  and  invariably 
unsuccessful.  Whether  it  be  in  either  the  upper  or  lower  jaw,  the  diffi- 
culties in  these  cases  may  frequently  be  overcome  by  extending  the  fixture 
over  or  around  to  the  opposite  side  of  the  arch,  and  then  obtaining  some 
form  of  anchorage  upon  that  side  also,  thus  imparting  stability  in  the 
fixation  of  the  entire  structure. 

A  practical  illustration  of  this  class  of  cases,  as  applied  to  the  upper 
arch,  wherein  the  greatest  difficulties  are  usually  encountered,  and  in 
which  the  base,  forming  a  saddle  to  support  the  missing  teeth  and  extend- 
ing transversely  across  the  palate,  together  with  a  Roach  attachment  in 
an  inlay  on  each  side  of  the  arch,  and  which  was  cast  of  clasp  metal  in 


>    "N 


Fig.  513 


one  piece,  is  shown  as  the  case  originally  presented  in  Fig.  513,  and 
after  the  completion  of  the  fixture  in  Fig.  514. 

While  a  proper  arrangement  of  the  channels  leading  from  the  sprue- 
wire  to  various  parts  of  the  saddle,  as  previously  indicated,  together  with 
an  observation  of  the  other  requirements,  will  usually  insure  a  successful 
casting,  if  any  great  difficulty  is  anticipated  or  encountered,  such  cases 
may  be  made  in  two  separate  pieces  or  castings — the  saddle,  which  may 
be  made  of  thin  coin  or  22-k.  gold  in  one,  and  the  somewhat  heavier  and 
thicker  piece  extending  across  the  palate — which  should  be  cast  in  clasp- 
metal— in  the  other,  and  the  two  then  subsequently  united  with  solder. 
To  insure  strength  in  such  joints,  however,  it  is  always  well  to  dovetail 
one  into  the  other,  as  will  be  subsequently  described. 


599 


The  same  condition  is  also  often  found  in  lower  cases,  and  successful 
fixtures  demand  a  similar  procedure  and  may  be  constructed  in  like 
manner.  Fig.  515  illustrates  a  typical  case.  In  the  lower  arch,  how- 
ever, the  saddle  should  be  cast  separately,  and  the  extension  to  the  oppo- 
site side  of  the  arch  made  of  round  clasp-metal  or  iridio-platinum  wire 
from  12-  to  14-gauge,  and  subsequently  soldered  to  the  saddle  and  clasp 
at  the  same  time. 

Or  a  casting  instead  of  a  wire,  providing  it  is  made  of  a  good  grade 
of  clasp-metal  and  sufficiently  heavy,  may  be  made  all  in  one  piece,  and 
is  recommended  by  some  because  of  being  better  adapted  to  the  con- 
formation of  the  arch,  and  yet  less  bulky  and  therefore  affording  less 
obstruction  to  the  movements  of  the  tongue. 

For  such  bars  and  clasps,  however,  and  for  all  cases  where  tough- 
ness and  resiliency  are  demanded  in  certain  parts  of  a  fixture,  draufn 


Fig.  oU 


zvire  or  rolled  plate  is  undoubtedly  better,  for  the  reasons  already  men- 
tioned. 

In  this  particular  case  the  molar  crown  with  the  "ball"  part  of  the 
Roach  attachment  for  the  opposite  side  was  made  first.  The  bicuspid 
crown  was  then  made  and  a  clasp  of  26-gauge  clasp-metal  adapted  to  it. 
The  bite  and  impression  with  these  in  place  in  the  mouth  were  then  pro- 
cured, and  when  the  model  was  obtained  and  mounted  upon  the  articu- 
lator, the  saddle  was  molded  in  wax  to  fit  the  model  and  the  clasp  and  to 
accommodate  three  Davis  crowns.  After  casting  the  saddle,  and  attach- 
ing it  to  the  anterior  bar  and  clasp  with  solder,  the  Davis  crowns  were 


6oo 


Vie.  516 


6or 

then  cemented  to  place,  thus  avoiding  the  use  of  vulcanite,  which  makes 
a  splendid  type  of  construction  where  the  display  of  gold  is  not  objec- 
tionable. 

The  extension  of  a  fixed  arm  cr  projection  per- 

Cxtension  Bar  manently   and    securely    attached   to   the    supporting 

Bridges.  teeth  at  one  end  by  means  of  crowns  or  inlays,  and 

resting  firmly  upon  the  ridge,  is  also  a  useful  means 

of  anchoring   removable   fixtures,   and   is   particularly   applicable   to  the 

casting  process  because  of  the  necessity  for  obtaining  a  close  adaptation 

of  the  saddle  or  removable  fixture  to  the   supporting  bar.     A  method 

devised  by   and  used   with  considerable   success   in   these   cases   by   Dr. 

H.  E.  S.  Chayes,  of  New  York,  was  described  at  length  on  page  102, 

Items  of  Interest,  for  February,  1909  (Fig.  516). 

The  intricacy  of  the  design,  however,  and  the  difficulty  of  manipu- 
lating 22-gauge  clasp-metal  to  meet  these  requirements  makes  the  use 
of  such  methods  more  or  less  impracticable  in  the  hands  of  the  average 
operator. 

More  generally  applicable  and,  in  some  respects,  better  results  are 
to  be  more  easily  obtained  by  utilizing  the  tube  and  split-post  method 
in  connection  with  Davis  crowns,  or  any  of  the  other  separable  dowel 
porcelain  crowns,  in  the  following  manner : 

The  crov>'ns  or  inlays  for  the  supporting  teeth  should  first  be  made 
separately  and  then  united.  In  this  connection  the  extension  bar  should 
not  project  beyond  the  supporting  teeth  farther  than  a  distance  equal 
to  their  combined  width.  In  the  case  to  be  illustrated  the  two  bicuspids 
were  crowned  with  Davis  crowns  with  cast  bases,  each  having  a  narrow 
band  as  previously  mentioned  in  connection  with  single-crown  work.  The 
bases  or  caps  for  these  were  then  soldered  together.  With  these  then  in 
place,  a  "bite"  and  impression  should  be  taken,  the  model  made  of  invest- 
ment material,  and  the  case  mounted  upon  the  articulator. 

Davis  crowns,  or  other  porcelain  teeth  of  similar  design,  should 
then  be  selected  and  ground  to  place  on  the  model,  and  to  fit  the  occlu- 
sion, allowing,  of  course,  sufficient  room  for  the  bar  and  saddle.  When 
so  ground,  short  tubes  should  be  made  to  fit  the  holes  in  the  porcelain 
crowns,  and  these  should  be  drawn  from  30-  or  32-gauge  platinum.  If 
desirable,  the  holes  in  the  porcelain  teeth  may  be  enlarged  to  anv  reason- 
able extent  with  small  stones  in  the  engine.  \\' hen  tubes  for  each  tooth 
have  been  made  and  fitted,  the  joint  should  be  soldered  with  pure  gold 
and  one  end  closed. 

Two  pieces  of  half-round,  or  "D"  wire,  of  iridio-platiiium  or  clasp- 
metal  should  then  be  placed  with  the  flat  sides  together  and  tacked  at 
one  end  only  with  solder.  This  may  now  be  placed  in  a  small  pin-vise 
and  turned  down  with  a  fine  file  until  the  split-post  fits  the  tube  snugly. 


6o2 

When  closed  tube  and  split-post  have  been  made  for  each  porcelain 
tooth  (and  these  may  be  made  and  supplied  by  the  manufacturer),  they 
should  then  be  trimmed  until  the  tube  projects  about  1-16  of  an  inch 
beyond  the  hole  in  the  tooth,  and  the  split-post  as  much  longer  as  the 
space  between  tooth  and  model  will  permit. 

A  small  roll  of  wax  should  then  be  placed  on  the  model  and  formed 
to  the  outline  of  the  desired  extension  bar,  being  careful  to  fit  it  closely 
to  the  abutting  crown  or  inlay.  When  trimmed  to  about  the  proper  out- 
line, each  tooth  with  tube  and  split-post  should  then  be  placed  in  position 
on  same.  The  soldered  or  closed  end  of  the  split-post  being  purposely 
left  lono-er  than  the  tube,  will  at  once  engage  itself  in  the  wax  and  remain 
there,  while  porcelain  tooth  and  tubing  are  being  removed,  thus  admitting 


Fig  517 


Kig518 


of  the  easy  detachment  of  both,  and  insuring  the  proper  relation  between 
the  split-posts  and  the  wax-bar,  for  the  subsequent  accommodation  of 
tubes  and  teeth.  It  must  be  observed,  however,  that  these  posts  are  per- 
pendicular and  parallel.  When  such  an  adjustment  has  been  obtained, 
the  wax-bar  should  be  removed,  the  sprue-wire  attached  and  the  cast- 
ing made  in  clasp-metal.  To  insure  a  strong  attachment  between  the 
ends  of  the  split-posts  and  the  casting,  however,  the  ends  projecting  into 
the  wax-bar  should  be  roughened  and  notched,  a  precaution  previously 
emphasized,  and  it  is  also  well  to  use  whiting,  or  to  slip  a  thin  piece  of 
mica  in  between  the  open  ends  of  the  split-posts,  in  order  to  preclude 
their  becoming  united  during  the  casting  process. 


6o3 

When  the  extension  bar  has  been  cast,  it  should  then  be  finished, 
fitted  to  place  on  the  model,  slightly  embedded  therein,  and  then  soldered 
to  the  supporting  crowns. 

This,  the  fixed  part  of  the  case,  when  finished,  should  be  placed 
in  position  in  the  mouth  and  a  bite  and  impression  taken  (Fig.  517). 
When  mounted  again  upon  the  articulator,  the  porcelain  crowns  should 
first  be  oiled  to  prevent  the  wax  from  sticking  to  them,  the  tubes  inserted 
into  the  holes  and  the  removable  saddle  then  made  in  wax. 

If  the  saddle  is  to  be  made  in  gold  by  casting,  which  is  usually 
preferable  because  of  using  an  all-porcelain  tooth,  as  soon  as  the  wax- 
base  has  been  formed,  the  porcelain  teeth  should  be  carefully  removed, 
allowing  the  free  e::posed  ends  of  the  tubes  to  remain  embedded  in  the 
wax ;  the  sprue-wire  is  then  attached  and  the  case  invested  for  casting, 
in  which  procedure  it  must  be  observed  that  the  tubes  are  thoroughly  filled 
with  investment  material. 


Fig.  519 

When  the  piece  has  been  cast  and  finished  (Fig.  51  Ha),  the  teeth 
should  then  be  cemented  to  place  (Fig.  5iSb),  after  which  the  fixed 
part  of  the  attachment  may  be  mounted  permanently  (Fig.  519a),  and 
the  removable  portion  placed  in  position,  when  the  mounting  has  become 
secure   (Fig.  519b). 

The  advantages  of  this  type  of  construction  lie  in  the  facility  and 
accuracy  with  which  the  fixture  may  be  made  and  the  strength  which  is 
to  be  obtained  by  the  casting  process,  together  with  the  ease  with  which 
tightening  of  the  removable  part  may  be  effected  at  any  time,  simply  by 
spreading  the  split-posts. 

The  removable  part,  or  saddle,  may  be  made  of  vulcanite  instead  of 
gold  by  simply  soldering  a  projecting  lip  of  metal  to  each  tube  before 
waxing  up,  as  a  means  of  insuring  attachment  of  tubes  and  then  waxing 
up,  removing,  flasking,  packing  and  vulcanizing  in  the  ordinary  manner. 

In  the  construction  of  bridges  of  this  type  it  must  be  remembered 
that  the  extension  bar  acts  as  a  lever,  and  that  the  tissues  upon  which  the 


6o4 

saddle  or  removable  part  of  the  case  rests  are  more  or  less  yielding; 
hence,  in  the  excursions  of  the  mandible,  the  supporting  teeth  receive 
stress  in  both  vertical  and  lateral  directions. 

Provision  for  overcoming  vertical  stress,  in  the  method  of  Dr.  Chayes, 
is  made  by  grinding  or  filing  off  of  the  top  of  the  extension  bar,  thus 
allowing  the  removable  fixture  to  rest  more  firmly  upon  the  gum,  while 
the  collapsibility  of  the  spring  accommodates  lateral  stress,  thereby 
relieving  the  supporting  teeth  to  a  marked  degree. 

The  same  provision  against  vertical  stress  is  also  to  be  obtained  in 
the  tube  and  split-post  method  by  simply  grinding  off  the  top  end  of  the 
split-posts  so  that  they  do  not  touch  the  bottom  of  the  tubes.  Similar 
provision  against  lateral  stress,  however,  is  only  to  be  obtained  by  having 


iMg  520 


the  saddle  as  wide  as  possible,  and  well  adapted  to  the  tissues  upon  which 
it  rests,  which  should  always  be  well  absorbed  before  the  introduction  of 
such  a  type  of  construction. 

A  more  extensive  case,  and  one  that  shows  the  possibilities  of  casting 
to  a  very  marked  degree,  is  shown  in  Fig.  520 

In  this  case,  a  fixed  bridge,  carrying  a  cap  with  a  tube  adapted  to  the 
root  of  the  central  incisor,  and  the  ball  of  a  Roach  attachment,  was  first 
made  and  mounted  (Fig.  521).  A  Davis  crown,  having  a  cast  base  and 
"split-post"  dowel,  was  then  made  to  fit  the  cap  on  the  central  incisor. 
The  model  was  then  obtained  and  the  saddle  made  in  two  separate  cast- 
ings, the  one  covering  the  ridge  being  cast  in  coin  gold,  and  that  extend- 


6o5 


Fitr.  521 


ing  across  the  palate  in  clasp-metal,  a  "dovetail"  joint  between  the  two 
being  provided  (Fig.  522).  These  two  castings  were  soldered  directly 
on  the  model  and  at  the  same  time  the  cap  for  the  Davis  crown  and  the 
tube  for  the  Roach  attachment  was  soldered.  All  of  the  teeth,  except 
the  Davis  crown,  were  then  attached  with  vulcanite,  and  this  one  tooth 
finally  mounted  with  cement.  The  completed  case  is  shown  in  Fig.  523, 
In  still  more  extensive  cases,  involving  the  replacement  of  teeth  on 
both  sides  of  the  arch,  as  illustrated  in  Fig.  524,  the  casting  may  be  made 
in  three  sections.  In  the  case  shown,  Roach  attachments  were  used  on 
gold  crowns  on  the  molars ;  the  two  saddles  covering  the  ridge  were  first 
cast   separately    of   five  per  cent,   platinum   in   pure   gold.     The   section 


Kit:.  0-2 


6o6 

covering  the  palate  was  then  cast  of  clasp-metal.  When  the  castings 
were  finished  and  fitted  properly  to  place  on  the  model  to  the  tubes,  and 
with  each  other,  the  teeth  were  then  attached  to  each  base  with  pure  gold, 
and  each  side  finished  separately  with  Jenkins's  prosthetic  body  and  gum 
enamel.  These  were  then  placed  in  position  on  the  model,  together  with 
the  palatal  section,  and  the  whole  invested.  The  three  sections  and  the 
tubes  were  then  united  with  20-k.  solder.  The  completed  case  is  shown 
in  Fig.  525 

By  this  means     porcelain  was  used   for  cosmetic  reasons,  and  yet 
the  resiliency  of  the  tubes  of  the  Roach  attachments,  and  of  the  palatal 


Fiji.  523 


section,  was  in  no  manner  modified  by  the  heat  of  the  furnace  in  fusing 
the  porcelain.  In  similar  cases,  where  the  teeth  are  to  be  attached  with 
vulcanite,  the  fixture  may  be  made  in  three  sections,  as  indicated,  or  cast 
in  one  piece,  with  clasp-metal,  as  may  be  preferred. 

In  lower  cases  of  similar  character,  the  two  saddles  may  be  made 
separately  and  subsequently  united  with  a  12-gauge  bar  of  clasp-metal, 
or  iridio-platinum,  which  is  regarded  as  the  best  procedure,  or  the  en- 
tire fixture  may  be  cast  in  one  piece,  as  shown  in  Figs.  526  and  5-7. 

While  castings  of  this  size,  and  even  more  extensive  ones,  such  as 
are  illustrated  in  Figs.  528  and  529.  may  often  be  made  in  a  single  piece, 
difficulty  in  removing  the  wax  from  the  model  without  endangering  its 
shape,  or  of  suitably  accommodating  it  in  the  flask  during  the  process 
of  mvesting,  may  indicate  or  possibly  even  demand  making  it  in  two. 


6o7 


or  even  three,  pieces,  and  subsequently  uniting  these  with  solder.,  which, 
as  previously  mentioned,  may  be  done  with  facility. 

Better  results  may  often  be  obtained  thereby,  however,,  than  are 
afforded  in  swaging,  and  the  time  required  in  the  making  of  models,  dies, 
counter-dies,  and  in  swaging  is  also  saved. 


Fig.  52-t 


P'itr.  525 


Fiji.  526 


Fig.  527 


Any  difficulty  encountered  in  removing  the  wax 

Of ercomina  Simple       base- from    the    model    just    prior   to   investing,    on 

Difficulties.  account  of  undercuts,  etc..  may  be  easily  overcome 

by  first  breaking  the  model  at  these  points,  antl  then 

reattaching  the  broken  piece  or  pieces  with  wax.     When  the  wax  base 

has  been  made  and  is  ready  for  removal  and  investment,  the  broken  pieces 

may  first  be  carefully  detacheci  and  the  wax  then  removed. 

Any  possible  distortion  of  the  form  and  shape  of  the  wax  during 
its  removal  from  the  model  and  subsequent  investment,  no  matter  how 


6o8 


thin  it  may  be,  may  also  be  easily  overcome  by  first  covering  it  over  with 
a  thin  layer  of  investment  material  while  on  the  model.  When  this  has 
crvstallized,  the  protected  wax  base  may  then  be  removed  and  the  invest- 
ment completed  with  ease  and  without  danger.  In  such  instances,  how- 
ever, the  protecting  la3^er  of  investment  material,  which  has  already 
crystallized,  should  be  well  moistened  before  the  fresh  mix  is  added. 


Fig.  528 


Fit;-  529 


The  usefulness  and  practicability  of  assembled 

Jfssembled  "abutment  pieces"  in  the  construction  of  removable 

Jlbutmcnt  Pieces,       fixtures   increase   in   proportion   as   the   size   of  the 

case  increases,  and  the  number  of  supporting  teeth 

decreases.     A  typical  application  of  the  practicability  of  this  principle 


6o9 

in  extensive  cases  is  illustrated  in  Fig.  529  where,  with  but  a  minimum 
number  of  remaining  natural  teeth  to  serve  as  supports,  all  of  the  ad- 
vantages of  a  "fixed"  structure  are  obtained  with  a  minimum  of  stress 
upon  these  teeth — any  one  of  which  possesses  the  combined  strength  of 
all.  Add  to  this  the  possibilities  of  restoration,  and  the  sanitary  condi- 
tion resulting,  and  it  is  evident  that  the  success  of  such  fixtures,  in  view 
of  the  possibilities  of  obtaining  accuracy  of  adaptation  by  the  casting 


Fig.  530 


process,  is  unquestionable.  In  this  case  inlays  were  made  for  the  molars 
on  each  side  and  an  ordinar}-  cap  and  dowel  for  the  cuspid  roots. 
These  four  pieces  were  then  united  with  a  12-gauge  round  clasp-metal 
wire,  having  a  vertical  split-post  attached  on  each  side  in  the  region  of  the 
bicuspids.  This  fixture  was  then  cemented  to  place,  and  the  removable 
one  then  made  with  a  broad  saddle  resting  upon  the  ridge  and  wire, 
and  tubes  to  engage  the  split-posts  (Fig.  530).  The  completed  case, 
with  removable  fixture  in  position,  is  shown  in  Fig.  531 

Kemooable  Jfttacbments  in  Combination  with  Porcelain. 


In  the  construction  of  removable  fixtures  involving  the  anterior 
teeth,  and  particularly  where  the  extent  of  absorption  demands  consider- 
able restoration,  any  form  of  attachment  which  is  adapted  to  the  require- 
ments of  anchorage,  and  zchich  zcill  Zi.'itlistajid  a  higher  fusijig  point  tJian 
that  of  pure  gold,  may  be  used,  and  the  casting  made  of  five  or  ten  per 


6io 

cent,  platinum  in  pure  gold.  When  such  a  casting  has  been  made,  suit- 
able  teeth  may  be  selected,  ground  to  the  proper  adjustment  and  soldered 
with  pure  gold,  after  which  the  case  may  be  finished  with  Jenkins's 
Prosthetic,  Brewster's  or  any  of  the  low-fusing  bodies. 

Where  the  type  of  attachment  used  will  not  withstand  the  casting 
of  this  percentage  of  gold  and  platinum  alloy,  the  casting  may  be  made 
to  fit  closely  around  them,  and  their  attachment  to  the  finished  piece  sub- 
sequently made  by  soldering. 


Fig.  531 


In  many  cases  this  is  an  advantage,  for  the  reason  that  the  attach- 
ments are  not  subjected  to  the  heat  of  the  furnace  in  fusing  the  porce- 
lain, and,  therefore,  retain  their  original  strength  and  resiliency. 

It  must  thus  be  observed  that  the  scope  of  casting,  as  applied  to  the 
whole  field  of  dentistry,  and  particularly  to  the  field  of  prosthesis,  has 
already  revolutionized  our  methods  of  practice,  and  seems  to  possess 
never-ending  possibilities,  and  in  the  light  of  our  present  achievements  it 
is  apparent  that  the  size  of  the  fixture  to  be  cast  and  the  percentage  of 
successes  in  casting  are  but  a  question  of  development. 

This  is  evidenced  by  the  fact  that  even  full  upper  dentures  of  de- 
sired and  uniform  thinness  are  already  being  successfully  cast  in  gold 
by  Drs.  Taggart,  Van  Woert,  Solbrig  and  others. 

V/hether  the  influence  of  the  casting  process  upon  the  molecular 


6ii 

arrangement  of  the  metals  and  alloys  so  used  for  full  and  very  large 
cases,  however,  will  admit  of  the  same  accuracy  of  adaptation  that  is  now 
obtainable  in  smaller  cases,  appears  at  present  to  be  somewhat  doubtful. 
It  seems  probable  and  reasonable,  however,  that  this  phase  of  the  casting 
process  is  also  but  a  question  of  development. 

In  this  connection,  the  "artificial  stone"  investment  material  sug- 
gested by  Dr.  Weston  A.  Price,  of  Cleveland,  or  something  similar, 
may  prove  helpful,  or  may  eliminate  such  doubtful  possibilities,  but  for 
smaller  work  its  sphere  of  usefulness  seems  limited. 

All  of  the  splendid  achievements  which  are  now  within  our  grasp, 
however,  and  those  which  are  to  follow,  have  been  made  possible  by  the 
genius  and  untiring  efforts  of  Dr.  W.  H.  Taggart,  of  Chicago,  to  whom 
the  profession  must  ever  accord  credit  and  should  always  remain  grateful. 


The  End, 


INDEX 


Abrasion,    390. 

Abrasion,     Extensive,    129. 

Absorption     Excessive,    395. 

Abutment   Pieces,   Construction   of,  409. 

Abutment    Pieces,    Dowel    Crowns    as,    458. 

Abutment    Pieces,    Gold    Crowns    as,   558. 

Abutment  Pieces,  Gold  Crowns  as  Posterior, 
457. 

Abutment    Pieces,    Inlays    as,    553. 

Abutment    Pieces,    Porcelain    Crowns,    as,  557. 

Abutments,  316,   327. 

Abutments,    Preparation   of,   329. 

Acid    Bath,    24. 

Accuracy    in    Model    Making,    302. 

Acme   Backing   Forceps,  the  150. 

Accurate  Fitting   Dowels,  229. 

Adaptation   of    Facings,   148. 

Adapting  Backing,    133. 

Adapting  Facing,    133. 

Adhesive   Wax,   39. 

Adjustment  of  Dowel,  191. 

Advantages  and  Disadvantages  of  Bridgework, 
317. 

Advantages    of    Cementation,    533, 

Alexander,   C.   L.,  351. 

Alignment,   140. 

Allen,  A.   B.,   140. 

Allen,  C.  C,  3.50,  358. 

Allen,   John,  256. 

All-Gold  Dummies,  380. 

Alloying,    14. 

Alloys,  16. 

Alloys,   Dorrance,   19. 

Alloys,  Fusible,    20. 

Alloys,  Use    of    Base    Metals   and,    555. 

Alloys   of   Gold,   16. 

All-Porcelain    Dummies,   4.50. 

Amalgam,   Application   of,   117. 

Amalgam,   Use   of,  220. 

Anchorage    or    Attachments,    580 

Annealing,    13. 

Anterior  Bridges,    427,    443. 

Anterior  Crowns,     223,     231. 

Anterior  Dummies,    371. 

Application  and  Construction  of  Dummies,  371. 

Application  and  Construction  of  Porcelain 
Crowns,    221. 

Application    of    .\malgam.   117. 

Application  of  Detachable  and  Replaceable  Fac- 
ings,   1.59. 

Application  of  Dowel  Crowns  Without  Plate  or 
Band.    196. 

Application  of  Facings  to  Bicuspid  Crowns, 
132. 

Application   of  Partial    Bands,    1.55. 

Application   of  Riveted    Facirirs,    156. 

Application  of  Saddle-back  Teeth  to  Bicuspid 
and    Molar    Crowns.    136. 

Application   of  the   Davis   Crowi\   251. 

Application   of  Removable     Crowns,     171. 

Application  of  the  Casting  Process  to  Bridge- 
work,  539 

Application  nf  the  Casting  Process  to  Crown- 
work,   517. 


Application  of  the    Inlra-dental    Band,    173. 

Application  of  the    Logan    Crown,    253. 

Application  to   Deciduous    Teeth,    124. 

Application  to  Fixed   Bridgework,   319. 

Application  to  Gold    Inlays,    496. 

Application  to  Gold    or    Porcelain    Work,    495. 

Application  to  Individual     Roots,     117. 

Application  to  Irregularities,    131,    171. 

Application   to   Removable    Bridgework,    326. 

Application  to   Separated    Molar   Roots,  115. 

Application  to   N'ulcanite    Work,    494. 

Approximal    Contact,   49. 

Articulation   and   Occlusion,   49,   331. 

Articulator,    Mounting   on,   337. 

Articulators,   Improved,   304. 

Artificial    Restoration    of   Gum,   374. 

Artificial  Teeth,  Insertion  of  Gold  Fillings  in. 
279. 

Ash's  Crown    Swaging   Device,   95. 

Assembling,    42.5. 

Assembling,  Finishing,  ^Mounting  and  Repair- 
ing,   425. 

Attaching   Facing  and  Cusps,   377. 

Attachment  and   Dummy   Combined,  385. 

Attachment   Inlay,   488. 

Attachment,   Methods   of,   49,  4.50. 

Attachment   of    Facing,    224. 

Attachment  of  Alolar  and  Bicuspid  Crowns  £i 
Root,   225. 

Attachment,  the    Condit.    500. 

Attachment,  the   Griswold,  ,504. 

Attachment,  the   Morgan,   503. 

Attachment,  the    Roach,   493. 

Attachments,  468. 

Attachments,   Construction    of,    336. 

Attachments,   Groove,    .351. 

Attachments,   Inlay,   354. 

Attachments,   or    Abutment   Pieces,    3.30,   3'ih. 

Attachments,   Partial    Crown.    347. 

Attachments,  Telescope,    361. 

.-\ttachments,   Temporary,    363. 

.\ttachments,  to    the   Natural   Crown,   .341. 

.\ttachments,    to   the    Roots   of   Teeth,   338. 

Autogenous    Soldering,   35. 

B 

Backing,    1.30,    .376. 

Backing,  Adapting,  1.3.3. 

Backing.    Forceps,    the    Acme,    150. 

Backing    of   Facing,    149. 

Backing    Soldering,    13.3. 

Backings,    Sectional,   .557, 

Baird    System,    102. 

Baird    Systems,    Hollinesworth    and,    12o. 

Baird,    W.    H..    102.   123. 

Bake,    Final,    26,8. 

Bake.    Primarv.    2a8. 

Baking.   461.   402. 

Band.    116.    1.30.    14.3,    227. 

Band    and    Dowel    Crown,    the   1.38. 

Band   and   Dowel,   With,   227. 

Band.    Preserving   Continuity   of,    127. 

Band,    Primary,    10.5. 

Bands,    .Application    of   Partial,    15.5. 

Bands.    Partial,    2.37. 


Bai,    Connecting,    446,    452. 

Base  Metals,  29. 

Bases,   \'ulcanite,  582. 

jjicuspid   Crowns,  :J24,   2.S2. 

Bite,   149. 

"Bite"    and  Impression,   ICG,    167,   336,  558 

Bite,    Impression   and,   2-:9. 

Blanks   for   Seamless   Crowns,    113. 

Blowpipe,    O.xy-Hj'drogen,   33. 

Bodies,     Foundation    and    Enamel.    268. 

Bodies,    Gum   Enamel,   261. 

Body   Building,   462. 

Body   Mi.xing,   263. 

Body,    Manipulation    of,    262. 

Body,   One  Grade  of,  264. 

Bonwill    Clasp,    the,   473. 

Bonwill,  W.   G.  A.,  5,  473. 

Boos  Method,   the,  166,  416. 

Borax,    26. 

Bo.x   Method,  164. 

Brass,    19. 

Brewer,    F.    A.,   177. 

Brewer    Method,    177. 

Brewster    Bridge    Teeth,    413. 

Brewster    Crown,    the,   213. 

Brewster,    R.,    213. 

Bridgeometer,    Evslin,    352. 

Bridges,  Anterior,    427. 

Bridges,   Extension,    316,    395,    402. 

Bridges,   Extensive.    428. 

Bridges,    Interrupted,   317,    392. 

Bridges,  Posterior,   428. 

Bridges,   Saddle,   317,  393,  428. 

Bridge   Teeth,    Roach  Wedgelock,   419. 

Bridgework,   Advantages  and  Disadvantages  of, 

317. 
Bridgework,  Application    to    Fixed,    319. 
Bridgework,    Application   to    Removable,    .326._ 
Bridgework,    History,    Development   and   Ethics 

of,  307. 
Bridgework,    Porcelain,    396. 
Bridgework,    Removable,    466. 
Brophy,    R.   C,   270,   277. 
Brown    Crown,   the,   8. 
Brown,    E.    Parmley,    8. 
P>ryan,    L.    C.    423. 

Bryant,    Emorv  A..   164.   181.   480,   508. 
Bryant   Method,   164.    181,   423,   508. 
Bryant   Method   of   Clasp  Attachment,  480. 
Buckley,    T.    P.,    22. 
Building   Body,   462. 
Building,    Carving  and   Baking,  461. 
BCttner  Crown,  the,  6. 
BGttner,  H.   W.,  6. 


Canals,    Preparation    of,    69. 

Cantilever    Rridees,    117. 

Capon,    F.   J!,   216. 

Capon,    W.    A.,    260. 

Caps.   Re-enforced,  2.3.5. 

Care   of  Dental    Brideework,    the,  511. 

Caries,    Extensive,   46. 

Carmichael,   J.   P.,   351. 

Carved  Cusp  and  Special  Die  Methods,  88. 

Carved  Cusps,   377,  .379. 

Carving,   461,   462. 

Carving   and    Contouring.    266. 

Carving    and    Swaeing,    122. 

Case,   C.   S.,  64.  4.31. 

Cast  Clasps.  583. 

Casting,   3.50,  552. 

Casting    Against    Porcelain,    532. 

Casting   Tapeart    Method    of,    .3.58. 

Casting  to    Surfaces    of    Metal.    555. 

Cavities   in   .Anterior  Teeth,   Formation   of.  545. 

Cavities  in   Postfrior  Teeth,  Forrnation   of,  544. 

Cementation,    Advantages    of,    533. 

Cement,  4.'',2. 

Cement   and   Gutta  Percha,   Cnmbminp,   298. 

Cervical    End.    149. 


Chloropercha,    Use    ot,   299. 

Christensen,    E.    G.,    96. 

Cigrand,    B.    J.,    13,    175. 

Cigrand   Method,   17.5. 

Clasp   Attachment,  the  Bryant  Method   of,   480. 

Clasping  Natural  Crowns,  584. 

Clasping  Porcelain  Crowns,  584. 

Clasps,    468. 

Clasps    Adjusted    to    Gold    Crown,    474. 

Clasps    and    Occlusal    Rests    in    Fillings,    473. 

Clasps    Applied   to    Porcelain    Work,    479. 

Clasps,    Typical   Application    of,    475. 

Clasps,   Use   of,   580 

Clasps    with    Occlusal    Rests    Applied    to    Gold 

Crowns,   47.5. 
Classification,    Principles    and    Requirements    of 

Dental    Bridgework,    315. 
Cleavers,    Use    of    Enamel,   64. 
Close,    S.    J.,   256. 
Coin   Gold,   16. 
Color,    141. 

Color   and   Harmony,    14i. 
Color,    Selection    of,    263. 
Coloring    Matter,    2.57. 
Colors,    Oil,    141. 
Colors,   Use  of  Oils,  265. 
Combination  of  Cast  Gold  and  Porcelain  Inlay, 

554. 
Combining    Cement    and    Gutta    Percha,    295. 
Composition,    Characteristics    and    Manipulation 

of   Porcelain    Bodies,   256. 
Compounding    Solder,    19. 
Condit    Attachment,    the,    500. 
Connecting   Bar,    446,    452. 
Constructing    .'\nterior     "Dummies,"   565 
Constructing  Posterior   "Dummies,"  559. 
Construction    of   Abutment   Pieces,   409. 
Construction    of   Attachments,   .3.36. 
Construction   of    Dummies,   337,   461. 
Construction    upon    Models,    194. 
Continuous     Cusps,     379. 
Contouring    and    Carving,    266. 
Convex    Saddle,    4.54. 
Cooling    after    Soldering,    34. 
Correction    of    Malposition,    384. 
Crown  and  Bridge    Tooth.     Steele,    420. 
Crown   and   Split    Post,    486. 
Crown,    Anterior,   223,   231. 
Crown  in   Furnace,   Placing,    270. 
Crown  in   Furnace,   Supporting,    269. 
Crown   Preparation    of,    262. 
Crown    Slitting    Forceps,    126. 
Crown   Swaging    Device,    Ash,    95. 
Crown,  The  Brewster,    21.3. 
Crown,   The  Brown,    8. 
Crown,  The  Biittner.     6. 
Crown,   The  Davis,   199. 
Crown,   The  Fellowship,    214. 
Crown,  Tlie  Foster,   4. 
Crown,   The  Gates-Bonwill,    5. 
Crown,   The  How,    7. 
Crown,   The  Howland-Perry,    5. 
Crown,  The  Logan,    7,    203. 
Crown,  The  Mack,    4. 
Crown,  The  Richmond,    6. 
Crown,  The   Sanger,     156. 
Crown,  The    Spaulding,    241. 
Crown,  The  Webb,    8. 
Crown,   The   Weston,    7. 

Crowns,   Attaching  of  Molar  and  Bicuspid,  225. 
Crowns,  Bicuspid,    224,    232. 
Crowns,   Dowel,    29.3. 
Crowns,   Jacket,    2.38. 
Crowns,  Molar,   224,  2.3.3. 
Crowns,   Mounted    with    Gutta    Percha,    Remov 

ing,   .300. 
Crowns  of   Sound  Teeth  Incising  Natural,   332 

.340. 
Crowns,  Primitive   Application    of.   2. 
Crowns,   Use    of    the    Davis    and    Logan,    250. 
Crnwnwork,   Technique  of  all  Porcelain,  241. 
Cruttenden,    H.    L.,    293. 


Cusp  Formation,    Processes   for,   87. 

Cusp    Formation    Without  ^lodels,    95. 

Cusp  Soldering,    'J'.i. 

Cusps,  lltl. 

Cusps,  Attaching    Facing    and,    377. 

Cusps,  Carved,    379. 

Cusps,  Continuous,    379. 

Cusps,   Swaged,   iJC. 

Cyanide    Solutions,    28S. 

D 

Davis   and    Logan    Crowns,    Use   of    the,   250, 

Davis,    C.    H.,   199,  25U. 

Davis    Crowns,   40S. 

Davis    Crowns,    .\pplication   of   the,   251. 

Davis   Crown,   The,   199. 

Davis-Townsend   Method,   418. 

Deciduous    Teeth,    Application    of,   124. 

Dental    Laboratories,    142. 

Detachable   and    Replaceable   Teeth,   407. 

Detachable    Facings,  531. 

Development    of    Dental    Bridgework,    307. 

Devitalization,    Feasibility    of,    54. 

Devitalization    of   Pulp,    327. 

Die  and    Die   Plate   Methods,  97. 

Die  Plate    Cusps,    .380. 

Die  Plate    Methods,   122. 

Die  Plates,  97. 

Dies,  lOS,    193. 

Dies,   Individual,   97. 

Dodez,   E.    \V.,  300. 

Dodez,   Rosin    Compound,   300. 

Dorrance    Allov,    19. 

Dorrance,   W.   H.,   19. 

Dowel,    Adjustment   of,    191. 

Dowel,  Crown,   Preparation   for   Band   and,   t>2. 

Dowel  Crowns,  293,   297,   339,  451. 

Dowel  Crowns    as   Abutment    Pieces,  4.58. 

Dowel  Crowns  \\'ithout  Plate  or  Band,  Ap- 
plication   of,    196. 

Dowel  Crown,   the   Band  and,   138. 

Dowel  Crown,   the  Plate   and,   188. 

Dowel  Crown  Without  Band,  Preparation  for, 
67. 

Dowel,  Plate    and,    68,    2.36. 

Dowel,    Separating   Cap   and,   184. 

Dowel,  with    Band    and,    227. 

Dowels,,  49,   137,   140,   193,  526. 

Dowels,   .\ccurate   Fitting,    229. 

Dowels,  Inseparable,    67,    199. 

Dowels,   Separable,   68,    215. 

Dowels,   Substituting  Sep?rate,  210. 

Dowels,   L'se    of    Two,    167. 

Dummies,  316. 

Dummies,  All-Gold,   .380. 

Dummies,  All-Porcelain,   4.59. 

Dummies,   Anterior,    37L   541. 

"Dummies,"    Constructing    Anterior,    565. 

Dummies,   Constructing    Posterior,   559. 

Dimimies,   Construction    of,    .337,    411. 

Dummies,  Gold,  565. 

Dummies,   Occlusal     Surface.    382. 

Dummies,   Posterior,   .375,  541. 

Dummies,   Replaceable  Crowns  Used   as,  568. 

Dummy   Combined,   Attachment   and,  385. 

Dunn,    .T.    E.,    .507. 

Dunn   ^fetliod.  .507. 

Duplicates,  531. 

Dwight   Facing.    163. 

Dwight   ^rethod.    179. 

Dwight,   W.    H.,   103,   179. 


Electric   Furnaces,   274. 

Enamel    Cleavers,    Use    of,    R4. 

Enamel,    ^^cthod    of   Removing,   "242. 

Eni^mel,    Removpl    of,   64. 

Engine   \\'ork,    4.30. 

Enelish   Tube  Teeth.  3. 

Ethics    of    Dental    Bridgework,    307. 


Evans,    George,   1.32,   241,  4.35- 

Evslin    Bridgeometer,   3.52. 

Evslin,    L.    E.,   3.52. 

Excessive    Absorption,    .395. 

Excising   Forceps,   Use   of,  184. 

Extension  Bridges,   316,    305,   402,    510. 

Extension   for   Support   of   Facing,   172. 

Extensive     Abrasion,   129. 

Extensive  Bridges,    428. 

Extensive  Caries,   46. 

Extensive  Destruction    of    Root,    192. 


Facing,  1.30,   168,  230. 

Facing,   Adapting,    133. 

Facing  and    Backing,     Replacement    of,    18.3. 

Facing  and    Cusps,    Attaching,    377. 

Facing,  Attachment   of,   224. 

Facing,   Backing    of,    149. 

Facing,   Dwight,    163. 

Facing,   Extension    for    Support    of^    172. 

Facing,   Mason,    160. 

Facing,  Roach,    161. 

Facing,   Soldering,    1.34. 

Facing,   Use   of    Flat   Back,    168. 

Facing,    With,   2.33, 

Facing,  NMth.-'ut,    2.34. 

Facings,  Adaptation    of,    148. 

Facings,  Application  of  Detachable  and  Re- 
placeable,   1.59. 

Facings,  Application   of  Riveted,   1.56. 

Facings,   Detachable,  531. 

Facings,   Fractured,    436. 

Facings,   Fracturing   of   Porcelain,    28. 

Facings,   Ordinary,  .568. 

Facings,   Replaceable,    566. 

Facings,   Replacement   of,   176. 

Facings,   Replacing  Bicuspid  or   Molar,    182. 

Facings,   Selection   of,   371,   3iC. 

Facings  to  Bicuspid  Crowns,  Application  ot, 
1.32. 

Facings,  L'se  of  Ordinary,  530. 

Facings,   With,   452. 

Facings,   Without,   4.52. 

Feasibility   of  Devitalization,   54. 

Feldspar,  2.57. 

Fellowship    Crown,  the,  214. 

Final    Bake,    268. 

Finishing.   94.   151,  1.55,   284,  4.35,  429,   464. 

Finishing,    Polishing   and    Mounting,    284. 

First    Application    of    Porcelain    Crowns,    '-. 

Fitting,  143. 

Fixed  Bridges,   -t41. 

Fixed   Bridgework,    334,    540. 

Flaskine,    3.59. 

Flasks,   Casting,   107. 

Flux,    25,   257. 

Fluxed   Wax.    Parr,    26. 

Foil   Gold.   280. 

Forceps,    Crown    Slitting,    126. 

Formation    of  Cavities   in    .\nterior  Teeth,  545. 

Formation   of  Cavities  in   Posterior  Teeth,  544. 

Forming  Blanks,    113. 

Forming   the    Matrix,   2-14. 

Forming  Wax    Filling,    3.58. 

Fossume,   F.   L.,   509. 

Fossume    Method,    .500. 

Foster  Crown,    the,   4. 

Foundation    and    Enamel   Bodies,  268. 

Fractured  Facings,  436. 

Fractured    Roots.    Treatment    of,    71. 

Fracturing  of  Porcelain    Facings,    28. 

Free  Exposure   of  the  Root,  .56. 

Furnace  Heating,    271. 

Furnace,  Placing   Crown    in,    270. 

Furnace.   Supporting  Crown  in,  269. 

Furnaces,  274. 

Furnaces,   Electric.   274, 

Furnaces,   Gas,     278. 

Furnaces.   Gasoline,    277. 

Fusible  Alloys.   »0. 


Fusible  Metal   Models,  346. 
Fusing,    271. 
Fusing  Points,   260. 


Gas   Furnaces,   278. 

Gasoline   Furnaces,   277. 

Gates-Bonwill    Crown,    the,    5. 

Gates,   W.    H.,   5. 

German    Silver,   20. 

Gold,    15. 

Gold,  Alloys   of,    16. 

Gold  and    Platinum,    17. 

Gold  as  a   Solder,  Pure,  442. 

Gold  Bases,  582. 

Gold,   Coin,    16. 

Gold  Crown,    Clasps   Adjusted  to,  474. 

Gold  Crowns,    533. 

Gold  Crowns  as   Abutment   Pieces,  553. 

Gold  Crowns  as  Posterior  Abutment  Pieces, 
457. 

Gold  Crowns,  Clasps  with  Occlusal  Rests  Ap- 
plied   to,    475. 

Gold  Fillings  in  Artificial  Teeth,  Insertion  of, 
27y. 

Gold  Foil,   280. 

Gold  Inlays,   Application  to,  496. 

Gold  or   Porcelain    Work,    Application    to,    495. 

Gold  Plating,   288,   430. 

Gold   Platinized,    17. 

Gold,   Pure,   272. 

Gold,  Recovering    and    Refining    Waste,    22. 

Gold,   Refining,    21. 

Gold,   Roman,    281. 

Gold   Soldering,    33. 

Gold   Soldering,    Pure,    33. 

Gold   Solders,    18. 

Grinding    Off  Pins,   235. 

Griswold  Attachment,   the,   504. 

Groove  Attachments,  351. 

Gum   Artificial    Restoration    of,   374. 

Gum    Enamel,    Bodies,    261. 

Gutta-Percha,  434. 

Gutta-Percha,   Combining     Cement    and,    208. 

Gutta-Percha,  Removing  Crowns  Mounted  with, 
.300. 

Gutta-Percha,  Use   of,   295. 

H 

Hard  Wax,  39. 
Head,   Joseph,   215. 
Heat,    Uniform.   27. 
Heating   Furnace,   271. 

Heating  Up   and   Burning  Out   Wax,  551. 
History    and    Development    of   Crownwork,   1. 
History,    Development    and    Ethics    of    Bridge- 
work,   307. 
Hollingsworth    and    Baird    Systems,    123. 
Hollingsworth,   .1.    G.,  99,  123. 
Hollingsworth   System,   09. 
How  Crown,    the,  7. 
How,  W.   S.,  7. 

How   and    Perry   Crown,    the,   5. 
Hygienic  Considerations,   328. 
Hypertrophy,   Treatment   of,  55. 

I 

Impression,    148. 

Impression   and    Bite.   229. 

Impression,    Bite  and,    106.    167,    336. 

Impressions  of  Root,  19.3. 

Improved    Articulators,    .304. 

Incisal    or   Occlusal    End,   149. 

Incising  Natural   Crowns  nf   Sound  Teeth,  340. 

Indications   for   Porcelain    Jackets,   2.39. 

Individual    Dies,    97. 

Inlay    Attachments,    354,    488. 

Inlays    as    Abutment   P'"ces,  513 

Inlays,    Pin-I,ocked,   555. 


Inseparable  Dowels,  67,  199. 

Insertion    of   Gold    Fillings   in   Artificial   Teeth, 

279. 
Insuring  Accuracy  of  Adaptation  to  Root,  294, 
Insuring  Adaptation   of  Root,   528. 
Interlocking    Occlusal    Rest,    490. 
Interrupted    Bridges,   317,   392. 
Intradental    Band,    ^Application    of    the,    173. 
Investing,  39,  153,   109,  359,  445,  549. 
Investing  and   Investment   Materials,   36. 
Investing,   Object  of,   36. 
Investing,    Precautions  Incident  to,  336. 
Investment,   Preparation   of,   41. 
Investment,    Preparing    Case    for,    38. 
Investment,    Requirements  of  an,    38. 
Iridium,    16. 
Irregularities,   Application   to,   131,   171. 


Jacket  Crown,   129,  2.38. 

Jackets,    Indications   for  Porcelain,  239. 

Johnson,    A.    G.,    64. 

Johnstone,  A.   P.,  25.5. 

Johnstone   Method,   255. 


K 


Kaolin,    257. 
Keefe,  J.  E.,  216,  3.30. 
Kelly,   J.   L.,   506. 
Kelly   Method,   506. 


Laboratories,   Dental,  142. 

Lanchaster,  H.  N.,  215. 

Land,  C.   H.,   2.38. 

Lathe    Work,   4.30. 

Lawrenz,   W.   F.,  300. 

Leaving   Pins   Exposed,   235. 

Lingual    Supports,   368,    4.52. 

Lingual    Supports,    Occlusal   and,   365. 

Liquid   Soldering  Fluid,  26. 

Litch,    W.   F.,   3.51. 

Logan  Crown,    Application    of  the,   2.53. 

Logan    Crown,  the,   7,  203. 

Logan    Crowns,    Use    of   the    Davis    and,    2.50. 

Logan.   M.   L.,  7,  203,  250 

Loose  Teeth,    Splinting,    553. 

Loque   Method,   the,    421. 

Lowry   and    Millett    Systems,    123. 

Lowry,  H.   L.,   101,    123. 

Lowry    System,    101. 

M 
Mack  Crown,    the,   4. 
Making   Porcelain    Blocks,  4.59. 
Making   Wax   Inlay,    547. 
Malformation,    47. 
Malformed    Teeth.    120. 
Malposition,   47,    171. 
Malposition,    Correction     of,    .384. 
Manipulation   of   Body,    262. 
Mason    Facings,   160. 
Mason,,    W.    L.,    160. 
Matrix.    Forming   the,   244. 
Metal  Models,   Fu.sible,   .346. 
Metals,    Alloys   and    Solders,    10. 
Metals,   Base.   29. 
Metals.    Noble    and   Base,    11. 
Method,  Box,    164. 
Method,   Bryant,    164. 
Method  of   Attachment.   49,   4.50. 
Method   of   Removing   Enamel,   242. 
Miller,  C.   W..   111. 
Millett,    Dr.,    100.    123. 
Millett    System,    100. 
Millett   Systems,    Lowrv    and,    123. 
Mitchell    Methods.    Underwood    and,    178. 
Mitchell.    Wm..    178,    216. 
Mixing  Body,   26.3. 


Model  Making,   Accuracy  in,  302. 

Model,   Original,    113. 

Model   Swaging,    11. 'i. 

Models,  37,   33(),  532,  538.  559. 

Models,  Construction     upon,     194. 

Models,    Preparing,   107. 

Molar    Crowns,    224,    2.S3. 

Molding    \\a.x   Base,  527. 

Morgan   Attachment,    the,  503. 

Morgan,    T.    B.,   503. 

Mould,   113. 

Mountng,  289,   425,   431. 

Mounting,   Finishing    and   Polishing,    284. 

Mounting   on    Articulator,   337. 

Mounting,   Permanent,    2U0. 

Mounting,   Temporary,    290. 

N 

Natural  Crown,    Attachments    to    the,    341. 
Natural   Crown,    Preparation    of,    352. 
Natural  Crowns  of  Sound  Teeth,  Incising,  340. 
Noble   and   Base    Metals,   11. 
Nyman,  J.    E.,  260. 

O 

Object    of    Investing,    36. 

Occlusal  and    Lingual    Supports,    365. 

Occlusal   Ends,    Incisal    or,    149. 

Occlusal  Rest,    Interlocking,  490. 

Occlusal   Rests   Applied  to   Gold   Crown,    Clasps 

with,    475. 
Occlusal   Rests   in    Fillings,   Clasps   with,   473. 
Occlusal   Supports,    365. 
Occlusal   Surface    Dummies,   382. 
Occlusion,  376. 

Occlusion  and    Articulation.   40. 
Occlusion,   Articulation    and,   331. 
Occlusion,  Unfavorable,    395. 
Oil   Colors,    141. 
One  Grade  of  Body.   264. 
Open    Face    Crown,    341. 
Opening   of   the   Bite.   386. 
Opening    the    "Bite,"  553. 
Ordinary    Facings,   568. 
Original   Model,    11.3. 
Ottolengui,   R.,  66,  .367,  48.3. 
Owens.  J.   R.,   202. 
Oxy-hydrogen    Blowpipe,    33. 


Paralleling,  Converging  or  Diverging  Teeth,  60. 
Parr    Flux   Wax,  26. 
Partial   Bands,    237. 
Partial    Crown    Attachments.    34V. 
Patented,     Manufactured    and     Special     .Attach- 
ments  in    Removable   Bridgework,   492. 
Perforated    Roots,    Treatment   of,    70. 
Permanent  Mounting,  290. 
Perry,    S.    G.,   .5. 
Peeso,    F.    A..   484. 
Peeso    Method,    484. 
Physo-Chemical    Aspect.   328. 
Pin-Locked   T"lays,  555 
Pins,   Cast.    561 
Pins    Grinding    Off.    2.3.". 
Pins    Exposed,    Leaving,    23.". 
''?ins.   Special,    561. 
I'lacing  Crown   in   Furnnce.  270; 
Tiate  and  Dowel.    68.     2.36. 
Plate   and    Dowel     Crown,    the,    1S3. 
P'ate  and   Pin    Altacliment,    349. 
Piatinf.   Gold.   2SS.   4.30. 
Platinized  Gold,   17. 
Platinum,    1.". 
Platinum   pnd   Gold,  7^ 
Platinum   Crowns.    45."i. 
Platinum   Solder.   IT,   442. 
T'latiniim   Soldering     33. 
Platinum,   LTse   of,   i."3. 


Polishing,    285. 

Polishing   and    Mounting,    Finishing,   284. 

Porcelain   Blocks,    Making,   4.59. 

Porcelain  Bodies,  Composition,  Characteristics 
and    Manipulation    of,    256. 

Porcelain,   Bridgework,    388,    439. 

Porcelain,    Casting  .Against,   532 

Porcelain  Compounds,   256,    -t42. 

Porcelain   Crowns,    444,    519. 

Porcelain  Crowns,  Application  and  Construc- 
tion   of,    221. 

Porcelain    Crowns   as   Abutment   Pieces,   557 

Porcelain   Crowns,    First  ^Application   of,   2. 

Porcelain   Faced    Bicuspids   and    Molars,    375. 

Porcelain  Facing,  Preparation  for  Shell  or 
Porcelain    Crown   with,    62. 

Porcelain   Facings,    Fracturing    of,    28. 

Porcelain  in  Effecting  Adaptation,  Use  of  Plas- 
tic  or    Mouldable,    255. 

Porcelain  Inlay,  Combination  of  Cast  Gold 
and,    554. 

Porcelain  Jackets,    Indications    for,    239. 

Porcelain,  Preparing  Crown  for  Reception  of, 
133. 

Porcelain,   Providing   for   Strength   of,   442. 

Porcelain,  the  Shell  or  Telescope  Crown  in 
Combination    with,    128. 

Porcelain   X'eneer,    Preparation    of    the,    246. 

Porcelain  Work,    213. 

Porcelain   VVork,    Application    to    Gold    or,   495. 

Porcelain  Work,    Clasps   Applied   to,    479. 

Porosity,   273. 

Posterior   Bridges,   428,  448. 

Posterior    Dummies,    375. 

Precautions  Incident    to    Investing,    .3.36. 

Preparation  for  Band    and    Dowel    Crown,    62. 

Preparation  for  Dowel  Crown  Without  Band, 
67. 

Preparation   for   Shell   or  Telescope   Crown,  57. 

Preparation  for  Shell  or  Telescope  Crown  with 
Porcelain    Facing,    62. 

Preparation   of  .Abutments,    329. 

Preparation   of  Canals,  69. 

Preparation   of   Crown,   262. 

Preparation   of   Investment,    41. 

Preparation   of  Natural    Crown,   .3.52. 

Preparation    of  Roots,    the.    52. 

Preparation   of  the    Porcelain    A'^eneer,    246. 

Preparing  Case   for   Investment,   38. 

Preparing  Crown  for  Reception  of  Porcelain, 
133. 

Preparing  Models,    107. 

Preserving  Continuity    of    Band,    127. 

Principle    of    L'nited   Abutments,    the,    508. 

Primary  Bake,    268. 

Primary   Band.    105. 

Primitive    .Application    of    Crowns,    2. 

Processes   for   Cusp   Formation,  87. 

Prothero,    J.    PL.   65. 

Providing  for    Strength   of   Porcelain,   442. 

Pulp,    Devitalization    of.   .327. 

Pure   Gold,   272. 

Pure  Gold  as  a   Solder,  442. 

Pure  Gold   Soldering,    .3.3. 

R 

Ready-made  Forms,   12.5. 

Recovering    and    Refining    Waste    Gold,    22. 

Re-enforced    Caps,    2.35. 

Refining   Gold.   21. 

Removable     .\ttachnients    in     Combination     with 

Porcelain.    609. 
Removable   Bridges,    440. 
Removable   Bridgework.    316.    J66. 
Removable    Bridgework    and    Partial    Dentures, 

579.  587. 
Removable   Bridgework.    .\ppIication    to,   326. 
Removable  Crowns.    .\nr>lication    of,    171. 
Removal    of    Enamel.    64. 
Removing  and   Repairing,    126. 
Removing  and  Soldering,    4.37. 


Removing  Crowns   Mounted  with  Gutta-Percha, 

300. 
Removing  Wax,   40. 

Repairing,  127,    176,    201,    215,    425,    436,    464. 
Repairing,  Removing  and,   126. 
Replaceable    Crowns    Used   as   Dummies,   568. 
Replaceable    Facings,  566. 

Replaceable    Facings,    Steele's    or    Evslin's,  569. 
Replacing   Bicuspid   or   Molar    Facings,    18:.'. 
Replacement  of  Facing    and    Backing,    183. 
Replacement  of  Facings,    176. 
Requirements    and    Technique    of    Crown    Con- 
struction, -43. 
Requirements    of  an    Investment,    38. 
Richmond,   C.    M.,  6. 
Richmond   Crown,   the,   6. 
Roach  Attachment,    493. 
Roach  Facing,   161. 
Roach,  F.   E.,  161,  419,  403. 
Roach  \\'edgelock    Bridge    Teeth,    419. 
Rohland,    C.    B.,    301. 
Roman    Gold,    281. 

Root,   Extensive  Destruction  of,  192. 
Root,   Free   Exposure  of   the,   56. 
Root,   Impression    of,    193. 
Root,   Insuring     Accuracy     of     Adaptation     to, 

294. 
Root  Preparation,   190,   198,   227. 
Roots,  Application   to    Individual,    117. 
Roots,  Application    to    Separated,    115. 
Roots  of   Teeth,   Attachments   to   the,    338. 
Roots,    Short,  536. 
Roots,   the    Preparation    of,   52. 
Roots,  Treatment   of  Perforated,  70. 
Royce,    C.    E.,    141. 
R.ubber   Tissue,    300. 

S 

Saddle  Back  Teeth  to  Bicuspids  and  Molar 
Crowns,    Application     of,     136. 

Saddle  Back   Teeth,    Use   of,   170. 

Saddle  Bridges,  317,  393,  428,  434. 

Saddle  Convex,    454. 

Saddle   Formation,   560. 

Saddle  From  a  Hygienic  Viewpoint,  the,  38, 
396. 

Saddle,  With,   448,   450. 

Saddle.   Without,  445,   450. 

Sand    Bath,    24. 

Sandarac    N'arnish,    Shellac    and,   299. 

Sanger    Crown,    the.    156. 

Sanger,    R.   M.,   156. 

Scott    Method,    114. 

Scott,  W.   P.,  114. 

Seamless  Method,   103,   123,  .346. 

Selection   of   Color,   263. 

Selection  of    Facings,   .371,   .376. 

Separable   Dowels,  68,  190,   21.5. 

Separating    Cap    and    Dowel,    184. 

.Separating  of    Teeth,    173. 

Sharp,    W.    M.,    110. 

Shell  or  Telescope  Crown,  in  Combination  with 
Porcelain,    the,    128. 

Shell  or  Telescope  Crown,  Preparation   for,  57. 

Shell  or  Telescope  Crown,  the,  4,  74,  293,  298, 
339. 

Shell  or  Telescope  Crown  with  Porcelain  Fac- 
ing,   Preparation    for,    62. 

Shellac   and    Sandarac    Varnish,    209. 

Short  Roots.   536. 

Shrinkage.   28,  259. 

Silica,   2.57. 

Silver,   German.   20. 

Silver  Solder,   20. 

Soft  Solder.   21. 

Soft   Soldering,    3.5. 

Solder,  Platinum.    17,    442. 

Solder,  Pure    Gold   as   a,  442. 

Solder,   Silver,    20. 

Solder.   Soft.   21. 

Soldering.  13,  23,  80,  1.31,  143,  1.51,  1.54,  169, 
226,  429. 


Soldering,  Autogenous,    35. 

Soldering,   Backing,    133. 

Soldering,   Block    Teeth,    29. 

Soldering,   Cooling    After,    34. 

Soldecing  Cusps,   93. 

Soldering  Facing,   134,   2.31. 

Soldering,   Gold,    33. 

Soldering,   Platinum,    33. 

Soldering,   Pure    Gold,    33. 

Soldering,   Removing    and,    437. 

Soldering  With    Investment,    31. 

Soldering  Without    Investment,    30. 

Solders,   17. 

Solders,    Compounding,   19. 

Solders,   Gold,    18. 

Solid   Cast   Cusps,   94. 

Spaulding,    E.    B.,   241. 

Splinting    Loose   Teeth,   553, 

Split,   Post  y\ttachment,    Tube    and,    484. 

Split,   Post,   Crown  and,  486.  • 

Split  Post,  Telescoping  Crown  and,   487. 

Steele   Crown   and   Bridge   Tooth,   420. 

Steele's  or    Evslin's   Replaceable  Facings,  569. 

Strength,    50. 

Stress,  48. 

Substituting    Separate     Dowels,     210. 

Supporting   Crown   in    Furnace,    269. 

Supports,   Lingual,    368. 

Supports,   Occlusal,   365. 

Supports,   Occlusal    and    Lingual,    365. 

Swaged    Cusps,   00. 

Swaging,  92,    110,    113. 

Swaging,    Carving  and,    122. 

Swaging   Device,    Ash    Crown,    95. 

Swaging   Model,    113. 

Sweating    Process,    34. 


Taggart   Method    of   Casting,    358. 

Taggart,   W.    H.,   210,   358,   .300. 

Technique   of  All  Porcelain   Crown   Work,  241. 

Teeth,  Attachments   to  the  Root  of,   .338. 

Teeth,   Brewster    Bridge,    413. 

Teeth,   Incising    Natural   Crowns    of,   340. 

Teeth,   Separation    of,   173. 

Teeth,   Soldering    Block,    29. 

Teeth,   Use   of    Vulcanite,    170. 

Telescope  Attachments,    361. 

Telescope  Crown  in  Combination  with  Porce- 
lain,  the   Shell   or,   128. 

Telescope   Crown,  Preparation  for   Shell  or,   57. 

Telescope    Crown,    the    Shell,   4,   203,    208,   339. 

Telescope  Crown  with  Porcelain  Facing,  Prep- 
aration   for    Shell   or,    62. 

Telescope  Crowns,  455. 

Telescoping,  50. 

Telescoping  Crown   and   Split   Post,   487. 

Temporary  Attachments,   .363. 

Temporary  Crowns,    217. 

Temporary  Mounting,    200. 

Therapeutics,   .53,   205. 

Thin   Wax   Bases,   528. 

Tooth,    Steele   Crown   and  Bridge,  420. 

Townsend,   E.    L.,   424. 

Townsend   Method,    424. 

Treatment  of    Fractured    Roots,    71. 

Treatment   of    Hypertrophy,    .55. 

Treatment  of    Perforated    Roots,    70. 

Treuman,    W.    H..    107. 

Tube   and   Split  Post  Attachment,  484. 

Tube   Crowns,   216. 

Typical   Application   of   Clasps,  475. 

U 

Underwood   and   Mitchell   Method,    178. 

Underwood,    C.    .T.,   178. 

Unfavorable    Occlusion,   .305. 

Uniform    Heat,    27. 

United   Abutments,   the   Principle   of,   .508. 


Use  of  Amalgam,   220. 

Use  of  Base    Metals    and   Alloys,    555. 

Use  of  Chlorapercha,   2'M. 

Use  of  Enamel    Cleavers,    04. 

Use  of  E.xcising   Forceps,    184. 

Use  of  Flat    Back   Facing,   HiS. 

Use  of  Gutta-Percha.    2U.j. 

Use  of  Oil    Colors.   2G.5. 

Use   of    Ordinary   Facings,  530. 

Use  of  Plastic    or    Mouldable    Porcelain    in 

fecting    Adaptations,    -~>Tt. 
Use  of  Platinum   in   Backing   Facings,   153. 
Use  of  Saddle    Back    Teeth,    170. 
Use  of  Davis   and    Logan   Crowns,   250. 
Use  of  Two    Dowels,    167. 
U^se  of  \'ulcanite,     220. 
Use  of  A'ulcanite   Teeth,   170. 


^'ar^ish.    .Shellac   and    Sandarac,    299. 
N'ulcanite    Bases,  581. 
Vulcanite  Teeth,    Use   of,    170. 


\ulcanite.   Use   of,   220. 

N'ulcanite  Work,    Application    to,   494. 

W 

U'allace,    .\.    H.,   4^5. 
\Va.\',   .Xdhesive,    >>'.). 
Wax   Backing,  561. 
Wa.x,   Filling,    Forming,    .358. 
Ef.        Wax,   Hard,    .30. 

Wa.x   Inlay,   Making,   547. 

Wax,   Removing,    40. 

W'ebb   Crown,    the,   S. 

Webb.   M.    H.,    8. 

Wedgelock   Bridge    Teeth,   Roach,  419. 

Weston   Crown,   the,   7. 

\\'eston,    Henry,    7. 

\\'illiams.    Dr.,    174. 

M'illiams'    ]Method,    174. 

N\'itli    Facing,    233,    452. 

Without    Facing.    234.    452. 

With    Saddle.   -448,    450. 

Without   Saddle,   445,    450. 


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